The invention discloses a modular heat preservation and sound insulation bearing wood wallboard and a construction method of an L-shaped wall. The modular heat preservation and sound insulation bearing wood wallboard comprises frame wood plates, straw plates, double-layer longitudinal studs, transverse studs, a bottom beam plate, a lower top beam plate, an upper top beam plate, nails, heat preservation plates, OSB plates, waterproof air-permeable films, waterproof air-permeable film joint sealing reversed coils, dampproof air vents, water guiding plates, double-layer joint sealing waterproof air-permeable films, an outside finish, gypsum boards, pipeline distributable cavities, wall top beam lapping plates, top beam lapping ports and intra-wallboard connection reinforcing plates. The frame plates are arranged at the two ends of the modular heat preservation and sound insulation bearing wood wallboard correspondingly. The multiple transverse studs are arranged between the frame plates uniformly. The straw plates are arranged between the frame plates and the transverse studs as well as between the adjacent transverse studs. The double-layer longitudinal studs are arranged between the straw plates. According to the modular heat preservation and sound insulation bearing wood wallboard and the construction method of the L-shaped wall, the structure is simple, the design is reasonable, operation is convenient, installation operation is remarkably simplified, the assembling speed is high, the industrialization degree is higher, the economic effect is good, and environment pollution is avoided.