The Sierpinski gasket structure is introduced into two-dimensional photonic crystal to design a new kind of photonic crystal——the Sierpinski quasi-fractal photonic crystal. By using finite-difference time-domain method, the transmission spectra of Sierpinski quasi-fractal photonic crystal with dielectric rods and air holes are calculated and analyzed respectively. The results show that the band gap exists on the condition of dielectric rods and incidence of TM wave only. The band gap property(bandwidth and central frequency) and characteristics of the pass-bands which exist in the band gap of Sierpinski circular-rods quasi-fractal photonic crystal with different dielectric constant and fill ratio are analyzed. Further more, the effects of different fractal series and dielectric-rod shapes on the transmission spectra and band-gap characterishis are simulated.