The negative refraction phenomenon in wavy two-dimensional (2D) photonic crystals (PC) is investigated with the iso-frequency surfaces of PC and incident medium. The finite-difference time-domain method is used to simulate the negative refraction of incident Gaussian beam with different wavelengths and incident angles. When the incident angle is set at 45 degrees, the linear relation exists between the negative refraction angle and the wavelength within the range from 1485 to 1530nm, which is suitable for the superprism effect. In order to increase the transmission when negative refraction happened at large incident angles, interface projection method is employed.