Photonic crystal (PC) polarization filter is a new kind of filter that can control the polarization state of the signal light by using the photonic band gap. It has important applications in optical fiber communication, optical sensing measurements, optical information processing and other fields. The channel number is an important parameter for polarization filter design. The more the channel number is, the greater the information capacity is. So it is conducive to system miniaturization. The influenced factors on channel number of 1D PC polarization filter are studied by using the optical transmission matrix method, the results show that: (1) The defect layer thickness is the key factor in affecting the channel number, and channel number N is a approximate linear function of the thickness D. In the wavelength band from 500 nm to 650 nm the function is N= 0.0035D+0.159; (2) The change of refractive index in defect layer also leads to the change of channel number, and the greater the refractive index is, the more the channel number is. (3) The changes of the numbers and the thickness of photonic crystal periodic layer cannot affect the channel number, however it can regulate the central wavelength of filter channels and influence the polarization degree and separation degree of polarization.