The utility model discloses a monitoring cubical switchboard partial discharge horizontally sensor, including be used for with bottom plate that the cubical switchboard is connected and with the dielectric layer of insulation as an organic whole is connected to the bottom plate, the sensor is still including being used for detecting discharge horizontally superfrequency detection module and transient state ground voltage detection module, superfrequency detection module and transient state ground voltage detection module fix in the dielectric layer, be connected through lead -out wire and external electricity respectively. The utility model discloses a superfrequency that the sensor has simultaneously detects and transient state ground voltage detection function, because fixed mounting on the cubical switchboard, compares with handheld mode, stability is good, and data collection precision is high, performance safe and reliable. Sensor fixed mounting is on the cubical switchboard, and monitoring results is reduced the manpower and has been avoided tester's the person dangerous by lead -out wire transmission to external monitoring instrument.