The invention discloses a passive composite sensor which comprises the components of an annular housing (100), a PCB (2) and a holding device (260), wherein the PCB and the holding device are arrangedin the annular housing; the circumferential inner annular surface of the annular housing (100) forms a measuring space. The passive composite sensor is fixed to a tested contact through the holding device (260). The tested contact penetrates through the measuring space. The holding device comprises a stroke guiding component, a pushing and compressing component and a stroke backstop component, wherein the pushing and compressing component can perform reciprocation in an in-ring direction or an out-ring direction. The stroke backstop component limits the highest motion stroke of the pushing and compressing component. The PCB comprises an electric field power acquisition module, a master control unit, a temperature measuring module and a current measuring module. The passive composite sensor realizes a technical effect of stably fixing the passive composite sensor on the tested contact.