The article proposes a measurement method to efficiently and accurately obtain the key terminal ballistic parameters (i.e., the hitting coordinates, the flight velocity, the flight direction angle of the projectile and the weapon firing rate) of small arms using the sparse distribution detector array. Compared with the traditional methods of uniformly and densely arranged detectors, this method greatly reduces the number of lasers and detectors required, thus saving costs. In addition, because the detector distribution can be non-uniform, installation and commissioning are more flexible and convenient. First, the detection principle and the composition of the system based on the propagation characteristics of the shock wave are described. Then, the measurement model of the system is established, and the calculation equations are derived by combining the relevant structural parameters and the shock wave propagation velocity. In addition, the systematic errors of the parameters such as the impact coordinates and the flight velocity are analyzed, and the effectiveness and practicality of the measurement method are verified by simulation. The simulation results show that in the effective target area of 10 m×10 m, the measurement error distributions of x and y coordinate values are the same, both decrease with the increase of the over-curtain time and increase with the increase of the extraction time of the shock wave propagation. The maximum deviation of x, y coordinate values is 1.55 mm. The azimuth error decreases with the increase of x coordinate difference, and the maximum azimuth error does not exceed 0.08°. The pitch angle error decreases as the difference of x coordinate and y coordinate increases, and the maximum error does not exceed 0.95×10^-3 °. When the target distance varies from 0.5 m to 2 m, the velocity error of the projectile gradually decreases as the target distance increases. The velocity error of the projectile shows a trend of first increases and then decreases as the difference of the x and y coordinates increases. The maximum deviation of the velocity of the projectile is 0.65 m/s. In order to quantitatively compare the proposed method with the measurement results of the light screen array, live fire experiments are conducted. Two sky targets and two sparse distribution detector arrays are placed alternately along the trajectory line, each with a target distance of 1.5 m. The wooden target is placed 1.26 m behind the sparse distribution detector array. Three high-speed cameras are placed on either side of the trajectory line and above the wooden target, respectively. The rifle is placed on a gun rack and 100 standard projectile shots are fired at a distance of 30 m from a start target of the six-light screen array. The coordinates of the center of the bullet hole on the wooden target are considered as the reference values, and the high-speed camera measurements are considered as the reference values of velocity and attitude angle. To verify the feasibility and validity of the proposed method, the sparse detection array measurements and the light screen array measurements are compared with each other and with the reference data. The measurement data of the proposed system show that the maximum deviation of coordinates is 2.4 mm, the average deviation of coordinates is 1.0 mm, the maximum deviation of azimuth and pitch angle is 0.128°, and the maximum deviation of flight velocity is 0.99 m/s. The proposed method reduces the average coordinate error by 35%, the average azimuth and pitch angle error by 31%, and the average velocity error by 33% compared with the six-light screen array measurement. The results show that the measurement method can meet the requirements for testing the terminal ballistic parameters of supersonic projectiles. Compared with the previous measurement system, it has the advantages of sufficiently large detection area, no detection blind area, low cost, easy installation and commissioning.