As a series of structural approximation need to be used in traditional geometry method, the model solving and accuracy analyzing of six-light-screen optical target based on this method are inaccurate. Here, a more accurate modeling and accuracy analyzing method based on plane equation was developed and a highly versatile engineering model and error transfer formula for six-light-screen optical target were deduced. Measurement accuracy decline caused by target distance and its error, light-screen tilt angle and its error, alignment error of light source and receiver, etc. were analyzed and compared under two kind of classical six-screen structural model. Sets of position and velocity measurement error distribution data and graphics in effective sensor area were acquired. A practical engineering layout of six-light-screen optical target with position measurement error less than 3 mm, and relative velocity measurement error less than 0.3% was proposed. This research can provide useful theoretical basis and data reference for practical design and accuracy estimation of six-light-screen optical target.