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.
