Objective: To optimize spherical aberration with toric intraocular lens (IOL), to study the IOL tolerance for random rotation and decentration, and to delineate the image formation rules for toric IOLs. Methods: This was an experimental research. The spherical aberration for toric IOLs was optimized with ZEMAX optical design software. The following steps were taken: ①Adjust the curvature of the IOL spherical surface to minimize the target. ②Optimize the IOL front surface for -0.26 μm, -0.1 μm and 0 μm spherical aberrations. The modulation transfer functio (MTF) was analyzed with a discrete distribution and the Monte Carlo method at pupil diameters of 3 mm , 4 mm and 5 mm. A Monte Carlo simulation analysis with 1 000 trials with IOL decentrations of 0 mm to 0.5 mm and rotation from 0°-5° randomy. Results: There was a 90% discrete distribution of MTF with a 3 mm pupil: the spherical aberrations of -0.1 μm and 0 μm MTF were ≥0.77 and ≥0.78, respectively, which were superior to a -0.26 μm IOL ≥0.55. A 90% discrete distribution of MTF with a 5 mm pupil: a -0.1 μm IOL≥0.35 and a 0 μm IOL ≥0.29 were superior to a -0.26 μm IOL ≥0.16. Monte Carlo simulation analysis of MTF: aspherical aberration of the toric IOL with a 3 mm pupil, either with 0.1 μm or 0 μm, showed superiorityover a spherical IOL under most circumstances, with good repeatability. With a 4 mm pupil, all three types of aspherical toric IOLs had an advantage over a spherical IOL. With a 5 mm pupil, the spherical aberrations of a -0.1 μm and 0 μm toric IOL had an advantage over a spherical IOL under all circumstances. A -0.26 μm toric IOL had a lower tolerance for decentration and rotation. Conclusions: Appropriate adjustment and optimal spherical aberration of the toric IOL can improve imaging quality and tolerance under error conditions in a model eye, and better optical quality is obtained in general situations.