The work aims to obtain the optimal process parameters in the lapping process of precision bearing steel balls based on variable-radius groove lapping method. Taguchi method was applied to test and optimize the parameters in the lapping process of steel balls based on variable-radius groove lapping method. With lapping pressure, abrasive size and abrasive concentration as the main influencing parameters, the orthogonal experiment was designed. With material removal rate (MRR), surface roughness (Ra) and ball degree error as evaluation indicators, the optimal lapping parameter combinations were obtained through the average response analysis and variance analysis. For material removal rate, the influencing factor of lapping pressure was the most significant followed by abrasive size and then abrasive concentration. For surface roughness, the influencing factor of abrasive size was the most significant followed by abrasive concentration and then lapping pressure. For ball degree error, the influencing factor of pressure was the most significant and other factors had less influence. The maximum MRR can be obtained under the conditions as follows: lapping pressure of 5 N/ball, abrasive size of 3,000# (5 μm) and abrasive mass fracture of 25%. The maximum MRR can reach up to 0.28 mg/h. The best surface quality can be got under the following conditions: abrasive size of 5,000# (3 μm), abrasive mass fracture of 25% and lapping pressure of 2.5 N/ball. When the lapping pressure is 0.5 N/ball, abrasive size is 3,000# (5 μm) and abrasive mass fracture is 50%, the ball degree error is small.