The invention relates to the field of vehicle overhauling space structures, in particular to a design method of an oversized overhauling space structure of a front-loading engine of a 10-meter public transport. The design method of the oversized overhauling space structure of the front-loading engine of the 10-meter public transport at least comprises two connection plates connected on two sides of the framework of an engine room, and is characterized in that a movable cross beam is detachably connected between the two connection plates through hexagonal head bolts and I-shaped nuts. Under a normal running status of a vehicle, due to the existing of the movable cross beam, the overhauling port of an engine cover and the overhauling port of a transmission are independent, and can be used independently. Once the vehicle breaks down, and a bigger overhauling space is needed, the hexagonal head bolts at the lower end of the movable cross beam are dismantled, the movable cross beam is taken out, the engine room and the overhauling port of the transmission at the rear end of an engine are connected into a whole, the overhauling space is greatly enlarged, and the problems that a maintenance space is small and the maintenance is difficult are solved completely.