We present the electronic structures and the basic properties of the first transition metal phthalocyanines (Pc) as well as their simulated STM images obtained by using the first-principles method. The simulated STM images show submolecular structures and reproduce the main features of the experimental images.The results show that the valence configuration of the metal ion has a strong influence on the STM images.At small tip bias voltage, unlike ScPc,NiPc and CuPc,wherein the central metal ions appear as a hole in the molecular images, the metal ion in other M Pcs STM images are the highlighted bumps. Moreover, we have studied the dependentce of the STM images of ScPc and NiPc molecules on the bias voltage, and predicted that the central metal ions in ScPc and NiPc images appear as bumps when the tip bias voltage is larger than -0.8V and 0.7V, respectively. The simulated STM images are interpreted as that the ScPc,NiPc and CuPc molecules have no significant dz2 character near the Fermi level, while the TiPc, VPc,CrPc,MnPc,FePc and CoPc systems have.