On the purpose of environment protection,two legislations-WEEE(Waste of Electrical and Electronic Equipment) and RoHS(Restriction of The Use of Certain Hazardous Substances in Electrical and Electronic Equipment) in Euro has been set up recently, which has been effective on July lst,2006.In coordinate with the requirement,there are worldwide activities that all electronic factories are busily engage in turning their products lead-freely.The Large companies such as Panasonic,Sony,Toshiba,Fujifilm have design their Timetable of lead-free.NEMI has a department to help some companies to start lead-freely assembly,some of them such as AIM,Alpha Metals,Celestica,Chip PAC FCI Electronics,IBM,Indium,Intel,ITRI,Johnson Manufacturing,Kester Solder, Motorola,NIST,SCI Systems,Storage Technology,Texas Instruments,Universal Instruments and Vitronics Soltec are developing their technology of lead-free.Under this background and combination with our company lead-free manufacturing without any equipment and instrument changing requirement,the article includes the study of the lead-free solder paste and relative lead-free production with focus on the critical process,and the optimizing of process parameter and ensuring of production reliability by introducing several new designs of experiment.The achievements of the study have significant meaning for the reference and utilization.The achievements as below: Compared lead/lead-free solder paste about their ingredient and characteristics,a nd analyzed the relative influence to the products and production.Designed solder printing comparison experiment result observation numeric expe riment to identify the process-optimized parameters of screen print.Introduced 9 curves design of experiment for confirming reflow working proces s-optimized parameters.Validated the effectiveness and reasonable of the process parameters by completing lead-free products pilot run and the relative reliability testing.The result is instructive and meaningful to the choice of lead-free solder,the 1 ead-freely production and the SMT technology.