In digital coherent receivers of high-speed optical fiber communication, the structure and performance of chromatic dispersion compensation block determines its practical value directly. A finite impulse response (FIR) filter with simpler even-symmetric structure is designed, and the effect of different lengths of FIR filter on chromatic dispersion compensation performance is discussed through numerical simulation. The results show that the length of FIR filter can be reduced to 65 percent of its theoretical maximum with only 1 dB penalty of optical signal-to-noise ratio (OSNR) at the receiver, in which the implementation complexity is decreased at a large scale while chromatic dispersion impairment can be compensated effectively.