Objective To develop MFT-2S protective mask with dual canisters and big-eye-window and to improve the three-grade system of protective equipment,so as to solve the problems on protective mask in environment with gas of high concentration.Methods MFT-2S protective mask was derived from MFT-2,with the advantages of MFT-2.The fixation intensity was effectively guaranteed by installing two sets of joint components and stainless steel clamps in the lower part of mask bilaterally.The sealing component was installed in communication component.Each canister was fixed at one side respectively.The fogproof lenses were reinstalled and the length of canister was increased properly.Results The results showed that,compared with MFT-1 mask,the inspiration resistance of MFT-2S mask decreased by a half,its total weight became about 50% of MFT-1 mask,and the leakage coefficient of MFT-2S mask was 0.005 percent.Its antidim character was improved and MFT-2S mask had better protective performance than MFT-2 by twice.Conclusion According to the transformed protection indices,MFT-2S mask,with the advantages of being light,simplified and standardized,can take the place of MFT-1 mask.