In order to reduce the risk of horizontal hydrogen jet explosion, the study was conducted on the explosion behavior and overpressure variation of horizontal high-pressure hydrogen jet by changing the distance between the nozzle and the ground. High speed camera was used to capture flame patterns, and pressure sensors were used to measure overpressure. The results indicate that the ground Kanda effect significantly affects the explosion of high-pressure hydrogen jets. As the height is low, the explosion flame is tightly attached to the ground. When the height is high, the explosion flame front is basically unaffected by the ground. The maximum displacements of the explosion flame and jet flame front decrease with the increase of the height between the nozzle and the ground, and then remains constant within a certain range. As the height increases, the overpressure curve changes from a single peak to double peaks, but the single peak value is larger while the values of double peaks are smaller. The peak overpressure decreases with the increase in the height, but becomes almost constant when the height is greater than or equal to 28cm.