The EM radiation and the shielding of PIFA of cellular phone to human head are studied by using the method of finite-difference time-domain (FDTD) In this paper. By compare the results of electric field distribution and special absorption rate (SAR) in the head model with two different shield settings, we know that the electric field and SAR distribution in the head model decreased obviously after the shield was added in. For the same input power, the SAR distribution on the coronal section of head model for monopole antenna is higher than that of planar inverse f antenna (PIFA).