Analyze the application of fool-proof in barrier-free design. Based on the basic concepts and implementation ideas of fool-proof， it pointed out the advantages of fool-proof introduced into product design， further discussed the necessity of fool-proof into barrier-free design taking the disadvantaged group as main service objective. Taking sanitary product as an example， it analyzed the application of fool-proof in barrier-free design from factors of human and machine. Fool proofing and barriers removing have the same essence. Application of fool-proof in barrier-free sanitary product design is a consideration of user′s needs. Machine factor relates to strengthening form contrast， choosing appropriate operation and adding necessary assist device to prevent user fool.