The invention discloses a detector for testing a tearing property of a food package. The detector comprises a chamber and a movable device, wherein the chamber comprises a fixed wall, a movable wall and a bottom plate; the fixed wall and the movable wall are vertically arranged at the upper side of the bottom plate; the fixed wall is provided with light source emitters with uncertain quantity; an annular hole is formed in the middle of the movable wall; the movable device comprises a sliding rod, a separation plate and a pressure sensor layer; the sliding rod penetrates through the annular hole in the middle of the movable wall; one end, located in the chamber, of the sliding rod is connected with the separation plate; the separation plate is parallel to the fixed wall; the pressure sensor layer is arranged at the other side of one side, connected with the sliding rod, of the separation plate; light source receivers with the quantity which is the same as that of the light source emitters are arranged in the middle of the separation plate and the pressure sensor layer. By adopting the detector disclosed by the invention, a tensile test is more adaptive to an actual condition of the food package in a transportation process and functions of a tensile machine are enriched; meanwhile, the light transmittance of the food package and the anti-rubbing performance of the food package can also be tested; furthermore, the percent of pass of the food package is further ensured.