In order to explore the influence of the waist radius b0 of the laser on the radiation characteristics of the collision between high-energy electrons and laser pulses, a compactly focused circularly polarized laser and single electron collision model was established based on the Lorentz equation and the electron radiation equation. The motion trajectory of electrons in Cartesian coordinate system is obtained by numerical calculation using MATLAB. Based on the results of simulation calculation, the relationship between the waist radius of tightly focused circularly polarized laser pulse and the peak radiation power between electrons is deeply studied. The results show that when the beam waist radius is small, the peak radiation power increases with the increase of the beam waist radius, and reaches the maximum peak radiation power at b0=1.7λ0. Then, the increase of the beam waist radius will cause the slow decrease of the peak radiation power. In addition, an optimal observation θ angle range［144°, 151.5°］ is found, and high radiation power can be observed in this observation range, and the collision between electrons and circularly polarized laser pulses can generate ultrashort attosecond pulses.