The invention discloses a U-shaped inclinometer and a mounting and embedding method thereof. The U-shaped inclinometer comprises a movable pipe, pipe covers, an inclinometer body, pipe joints and a U-shaped pipe. The U-shaped inclinometer is characterized in that guiding grooves are formed in the inner surface of the inclinometer body at intervals of 90-degree angles; and guiding projections are arranged on the outer surface of the inclinometer body; the diameter of the movable pipe is greater than that of the inclinometer body; the movable pipe is in screwed connection with a portion, which is exposed out of a soil surface, of the inclinometer body; the diameter of each pipe joint is greater than that of the inclinometer body; grooves are formed in the inner surface of each pipe joint and correspond to the projections on the outer surface of the inclinometer body; and four riveting holes which are perpendicular to one another, are formed in each pipe joint by an electric hand drill and do not affect the guiding grooves are used for connection; and the U-shaped pipe is connected with the inclinometer body through the pipe joints. The U-shaped inclinometer is simple in structure and convenient to operate, and can be used for pipe dredging and water drainage; the inclinometer is protected against being damaged; and the measurement precision is improved.