The speed, precision and stability of inversion algorithm are research emphasis in the field of particle measurement. To counter the problems such as burrs, false peaks and concussion etc. in the process of inversion with traditional Chahine algorithm, an improved algorithm that combines regularization theory with Chahine algorithm was used to reconstruct particle size distribution. A new linear equation was constructed by introducing the regularization theory, the regularization parameter was determined by using L-curve, and Chahine algorithm was used to solve the linear equations. Simulation and experiment results show that the improved algorithm overcomes the disadvantages of traditional Chahine algorithm and improves the stability and gliding property of inversion results. Measured results of standardized polystyrene microsphere is measured by using the improved algorithm, which shows that the relative errors for median diameter D50 is within 2%, and D10, D90(characterize broadening of distribution curve) are both within 5% when the number of inversion is 15 000. In addition, the inversion time is less than 1 minute, which meets online particle size measurement.