Horizontal supporting leg safety control method and system and crane

The invention belongs to the field of engineering machinery, and provides a horizontal supporting leg safety control method and system and a crane. The horizontal supporting legs comprise a first-stage horizontal supporting leg and a second-stage horizontal supporting leg; the second-stage horizontal supporting leg is connected with the first-stage horizontal supporting leg and freely stretches out and draws back in the first-stage horizontal supporting leg; the control method comprises the following steps: acquiring a telescopic instruction for a horizontal supporting leg and a vertical supporting leg; acquiring telescopic position information of the second-stage horizontal supporting leg, and judging whether the position of the second-stage horizontal supporting leg is within a preset range or not according to the acquired telescopic position information of the second-stage horizontal supporting leg; and if the position of the second-stage horizontal supporting leg is not within the preset range, the vertic