The natural rubber latex modified by polyorganosiloxane was produced by the methods of grafty copolymerization and blending with the solubilizing agent taking part in the reaction. The colloid properties, film structure and rubber films mechanical properties of the natural rubber latex modified by polyorganosiloxane were researched. The suitable conditions and technical methods of modification were determined. The effect of the kinds and contents of silicone, the kinds and contents of coupling agent, NR latex concentration, reaction temperature, reaction time on the monomers conversion and monomers graft percent of graft copolymerization had been studied. At the same time, the effect of the factors on graft copolymerization had been analyzed by using the statistical analysis of orthogonal experiment. The results showed that the optimum reaction conditions were as follows: the NR latex concentration was 50;, reaction temperature was 55 oC, reaction time was 4 h, VD4 was better than D4, the content of VD4 was 1;(occupy rubber), A-171 was the best coupling agent among KH-550, KH-570, A-151 and A-171, and the content of A-171 was 0.03;(occupy rubber). According to the above condition we can obtained the modified NR latex which had better general properties. Besides, modified NR latex was studied by DSC and IR. IR proved that poly-organosiloxane definitely grafted onto NR. Because the poly-organosiloxane has the special structure, so the polyorganosiloxane has many good properties such as high-temperature and low-temperature resistance, radiation resistance, weathering quality, oxidation resistance, high-air permeability, low surface energy and physiologically indert. The new material which contain the merit-difference behavior of both organic siloxane and NR latex was gained. With this new material, we can reduce the allergic reaction of the protein in the NR. From this point, we can accelerate the usage of the NR latex in the area of the medical products.