The invention provides a lateral non-support pile plate type soilless subgrade of a highway and a construction method thereof, and relates to the technical field of novel highway construction technologies. The lateral non-support pile plate type soilless subgrade of the highway comprises a plurality of prefabricated section plates, cast-in-place wet joints which are formed among the prefabricated sections, prefabricated pipe files, braking piers, connecting devices and connecting end cover beams. According to the lateral non-support pile plate type soilless subgrade of the highway, a traditional railway pile plate structure is improved, and the properties of the highway are utilized, thus creating a complete new lateral non-support pile plate type soilless subgrade structure of which the general applicable span is 5-8m; the complete new lateral non-support pile plate type soilless subgrade structure shows high superior technology and economy on a soft soil foundation which is strict in subgrade deformation control, and sections where the soil filling height is small and a bridge cannot be constructed; a subgrade structure form easy for popularization is brought; each braking pier is arranged in the middle of each section to effectively bear horizontal load; the piles, the braking piers and the plates are not completely fixedly connected through the pile piles, the braking piers and the special connecting devices for the piles, so that the temperature adaptability is high, and the structure safety is ensured.