The invention relates to a detection apparatus for a neutron flux and a temperature of a reactor core. The detection apparatus comprises an assembly housing, a self-powered neutron detector set, an internal sealing structure, a connector and a terminal portion sealing plug, wherein the self-powered neutron detector set is fixed inside the assembly housing and comprises N self-powered neutron detectors, the N self-powered neutron detectors are uniformly arranged at intervals from bottom to top along the axial direction of the assembly housing, the connector is sealedly fixed on the upper end of the assembly housing, the terminal portion sealing plug is sealedly fixed on the lower end of the assembly housing, the internal sealing structure is sealedly fixed in the internal of the assembly housing positioned above the self-powered neutron detector set, and the armoured cables of the N rhodium self-powered neutron detectors are bundled up and fixed, upwardly extend along the axial direction of the assembly housing, penetrate through the internal sealing structure, and finally are fixed on the pin of the connector. According to the present invention, the neutron flux change of the reactor core can be rapidly responded, the reactor core neutron flux and the fuel assembly outlet temperature can be real-timely measured, and the design requirements of the transmission cable can be reduced.