A method for detecting a minimal erythema dose includes: detecting a pigment index of a body to obtain a predetermined minimal erythema dose and a predetermined erythema generation index； obtaining a dose value of a UV light source； detecting a redness situation of a skin area of the body by a first time to obtain a first redness index； applying a UV absorption material having an SPF on the skin area； irradiating a UV light from the UV light source on the skin area and detecting a redness situation of the skin area by a second time to obtain a second redness index； when a difference between the first and second redness indexes is larger than the predetermined erythema generation index, obtaining a time value between the first and second detecting steps； and obtaining the minimal erythema dose of the body according the dose value, SPF and time value. The invention can know the dose of the actual UV light that the skin of the body can resist by correcting the minimum erythema dose of the body.
