Based on the channel response of time-interleaved photonic analog to digital conversion (TIPADC) system, the relationship between photodetection response and channel mismatches, as well as its effects on correction of mismatches is analyzed. The simulation is also performed. The results show that the influence of channel mismatches is irrelevant to the frequency when the photondetection response do not induce the crosstalk. In this case, the mismatch correction can be achieved with mismatch parameters obtained at a single frequency. In comparison, in the situation that the photondetection response can cause the crosstalk, the channel response under different gains has the same proportion change, while the channel response at different time mismatches changes in different proportions. Thus, the gain mismatches can only be corrected through mismatch parameters obtained at a single frequency.