Motion measurement was a key method to get characteristic and dynamic parameters of MEMS resonator in every moment. The results of measurement gave important reference to MEMS designation. In this paper
an algorithm based on block matching was designed so that it was insensitive to frame-to-frame intensity variations. MEMS motion process is analyzed using the algorithm. The offered solution achieved nanoscale accuracy by always employing a small and fixed number of computations
independent of the iterative method. The amplitude-phase curve of MEMS in special driving frequency was got. Experimental results indicate that the repetition of measurement is 5nm.