The invention discloses a device for checking a water blocking capacity of a cable connector. The device comprises a humidity sensor which is located in the cable connector of a cable to be detected in a water tank, a simulation cable which is electrically connected with the cable to be detected and has a type the same as that of the cable to be detected, a through transformer, a thermocouple sensor, an RFID (Radio Frequency Identification) electronic tag and a radio frequency identification and receiving terminal, wherein the humidity sensor is used for measuring the humidity in the cable connector and acquiring humidity data; the RFID electronic tag is used for reading the humidity data and sending the humidity data to the radio frequency identification and receiving terminal; the through transformer is used for generating current and enabling the simulation cable and the cable to be detected to be at a loaded state; the thermocouple sensor is used for monitoring temperature on the simulation cable; the radio frequency identification and receiving terminal is used for receiving the humidity data and monitoring a water permeation condition of the cable connector of the cable to bedetected. According to the device disclosed by the invention, non-contact type cable water permeation and condition monitoring is realized and practical convenience is provided for workers.