A problem about the chip changing tactics during the depositing process of multiplayer optical coatings that monitoring by separating control technique was investigated.The effect of different chip changing tactics on the optical properties of deposited coating was analyzed.The conclusion was educed that the chip changing tactics is also a key factor to the multiplayer optical coating depositing process.A new way that determines the optimal chip changing tactics by optimization principle and computer simulation is put forward and some relative computer programs are designed.The experimental results,from a coating-depositing machine which takes reflectance turning point monitoring approach,show that this program can search the optimal chip changing tactics and it is of guiding significance to deposit multiplayer optical coatings.