The utility model discloses an auxiliary vehicle frame of a chassis of a sand solidification vehicle. The auxiliary vehicle frame comprises a vehicle beam, five grass inserting box and a grass inserting box lifting/folding mechanism. The auxiliary vehicle frame is connected with a main vehicle frame by a bolt, so it is easy to install and disassemble a grass transmission mechanism. The vehicle frame comprises a cross beam and longitudinal beams. Two grass inserting boxes are arranged on two sides of the longitudinal beams and one grass inserting box is arranged on the back end. The lifting/folding mechanism comprises a long-stroke hydraulic cylinder, a short-stroke hydraulic cylinder and a hinged support. The cross beam is used for linking the left and right longitudinal beams, thereby form a whole framework and ensuring the vehicle frame has enough torsional rigidity. The cross beam is riveted to the longitudinal beams. The grass inserting box is hinged to the longitudinal beams. Via the lifting/folding mechanism, lifting, internally folding, laying down and externally stretching for the grass inserting boxes can be achieved.