The invention provides a walking steering mechanism and a seepage-preventing ditch cast-in-situ forming machine and belongs to the field of agricultural machinery. The walking steering mechanism comprises a walking assembly, a connection assembly and a driving device. The walking assembly comprises a first walking component and a second walking component which are parallel with each other. The connection assembly comprises a first connection rod and a second connection rod. The two ends of the first connection rod are connected with the first walking component and the second walking component in a rotary manner correspondingly. The two ends of the second connection rod are connected with the first walking component and the second walking component in a rotary manner correspondingly. The driving device is fixedly connected with the first connection rod. Under the action of the driving device, when the first connection rod is made to rotate relative to the first walking component and the second walking component, steering is achieved. The walking steering mechanism is simple in structure and simple and convenient in steering form. The seepage-preventing ditch cast-in-situ forming machine provided with the walking steering mechanism has a certain steering function; work limitation of the seepage-preventing ditch cast-in-situ forming machine is lowered; and the seepage-preventing ditch cast-in-situ forming machine can perform higher work potential.