We propose and optimize the antireflection coating composed of a row of tapered dielectric waveguides for two-dimensional air hole-type photonic crystal negative refraction slab lens. The image quality of the lens with the antireflection coating is improved. The simulation result using finite difference time domain method shows, at the working frequency leading to the effective index neff=-1, the reflection rate of the surface of photonic crystal with anti-reflection coating is reduced to below 1% in the range of incident angle less than 23 degrees.