The quasi continuous wave laser of 150 watt was used to weld stainless steel with 0.2 mm thickness. Through orthogonal experiment of laser welding process parameters, the tensile strength and sealed of welds met the requires. Tensile strength testing, inner structures analysis, hardness test were carried on the welded joint. The test results show that the main parameters on tensile strength are pulse width, followed by peak laser power. The maximal tensile strength reached 434 MPa. No pores and crack appeared in welds, microhardness was HV 254-256, which was bigger than the base metal. The sensor shells were welded and sealed character was tested, the test result showed that the sealed welds met the requires of 5 atmospheres.