The invention relates to an adjustable well lid with the outer portion being square and the inner portion being round and a mounting and adjusting method of the adjustable well lid. The adjustable well lid comprises a well lid body with the outer portion being square and the inner portion being round on the upper portion, independent
load bearing modules on the lower portion and adjusting bolts connected and supported between the well lid body with the outer portion being square and the inner portion being round on the upper portion and the independent
load bearing modules. The number of the independent
load bearing modules is four, and load bearing portions are located on a roadbase. Each adjusting bolt is composed of a bolt rod on the lower portion, an integrated nut in the middle and anunthreaded rod on the upper portion. The bolt rods are in threaded connection with reserved screw holes in the load bearing modules. The
diameter of each integrated nut is larger than the aperture ofa corresponding reserved through hole in the well lid body, so that the well lid body with the outer portion being square and the inner portion being round on the upper portion is flushed with the roadbase. The unthreaded rods penetrate through the reserved through holes of the well lid body with the outer portion being square and the inner portion being round, and a clamping opening is formed inthe end face of each unthreaded rod. According to the adjustable well lid, various possibilities that problems appear in the stages of construction, use and maintenance are avoided, meanwhile, operation is convenient and economical, and daily roads are safe to use and comfortable.