In this paper, implantation of indium atoms into silicon forming pn juction by Nd-YAG pulse laser irradiation was reported. The indium depth profile in silicon has been determined by secondary ion mass spectrscopy (SIMS) and Rutherford backscatting spectroscopy (RBS). The results can be ascribed to a qualitative model for the physical process of implantation indium in 20ns pulse laser irradiation. Namely, if the laser energy density exceeds a certain threshold, there exist two parts at the surface layer of silicon, silicon-indium molten mixture and liquid state silicon. But only the liquid state silicon layer exists at the surface if the laser energy density does not reach that threshold. The pn juction has good properties revealed by means of I-V and C-V measurements. The results of deep level transient spectroscopy (DLTS) show that there are two kinds of defects in pn juction. One kind of the defects (E1) disappears at 600℃, 60s in rapid thermal annealing (RTA) and the study shows that the defect E1 may be the impurity-vacancy complex. The other defects E2 would not disappear in RTA and may be related to the dislocations.