The invention discloses a liquid hydrogen filling device. The liquid hydrogen filling device comprises a hydrogen filling gun, a hydrogen filling port and a handle mechanism. The hydrogen filling guncomprises a hydrogen filling gun external pipe, a hydrogen filling internal pipe slidably arranged on the inner side of the hydrogen filling gun external pipe and a locking sleeve slidably arranged onthe outer side of the hydrogen filling gun external pipe. The handle mechanism comprises a push rod rotatably connected with the hydrogen filling gun external pipe. The push rod is connected with thelocking sleeve and the hydrogen filling internal pipe through a first connecting rod and a second connecting rod correspondingly. The push rod rotates to drive the first connecting rod to push the locking sleeve to slide to the hydrogen filling port to lock the hydrogen filling gun to the hydrogen filling port first and then drive the second connecting rod to push the hydrogen filling internal pipe to slide to the hydrogen filling port to open a filling channel in the hydrogen filling internal pipe and the hydrogen filling port so as to ensure that the hydrogen filling gun and the hydrogen filling port communicate in a sealed mode in the liquid hydrogen filling process. Leakage of liquid hydrogen is prevented. The safety of the liquid hydrogen filling process is ensured.