Electrical properties and phase structures of (Si+N)-codoped Ge2Sb2Te5 (GST) for phase change memory are investigated to improve the memory performance. Compared to the films with N or Si dopants only in previous reports, the (Si+N)-doped GST has a remarkable improvement of crystalline resistivity of about 104mΩcm. The Fourier-transform infrared spectroscopy spectrum reveals the Si-N bonds formation in the film. X-ray diffraction pattes show that the grain size is reduced due to the crystallization inhibition of the amorphous GST by SiNx,which results in higher crystalline resistivity. This is very useful to reduce writing current for phase change memory applications.