Experiments of laser aided direct metal deposition of 1Cr13 martensitic stainless steel thin walls are carried out. Thermal histories of two specified points in the substrate are recorded during the whole deposition process. Microstructure and microhardness in the vertical direction of the thin walls are observed and tested respectively. The results show that the microstructure and mirohardness distribution in the martensite stainless steel parts made by laser aided direct metal deposition usually exhibit specific features because of the multilayer deposition process. Microhardness near the joint region is higher than 350 HV due to the exist of pearlite. However, the microhardness in the upper region is about 200 HV.