The invention relates to a method of cast-in-place plate type platform wall construction. The method aims to avoid the influence of backfilling sedimentation of large excavation of existing line roadbeds when a low platform is heightened, solves the problem of short construction period, reduce manufacturing cost and improves construction efficiency. The hole digging pile form is adopted, short columns are fixedly connected to the upper portion, breast boards are arranged on the sides of the short columns, non-frosting heaving medium sand or rough sand is filled back to the rear of the boards,longitudinal expansion joints are arranged on the breast boards every 18 meters, and water drainage holes are preserved in the lower portions of the boards. According to the method, construction is simple, the manufacturing cost is low, and construction is easy.