The invention discloses a steel rail detection method for railway construction. The method comprises the steps that S1, detection preparation is conducted, specifically, a detection vehicle is placed on a steel rail, a detection block is connected with the steel rail in a clamped mode, a contact block is connected to the top face of the steel rail in an overlapped mode, and a first rotating rod and a second rotating rod are located on a same straight line, so that follow-up detection is facilitated; and S2, primiary detection is conducted, specifically, balls slide along the top surface of the steel rail, when the balls meet a deformation position of the steel rail in the vertical direction, the position of a liquid level plug in a liquid level pipe is changed, and the deformation degree and position of the steel rail are known. According to the invention, the deformation degree of the steel rail is determined by a deformation detection assembly, the internal damage condition is detected by a flaw detection assembly, the detection range is narrowed, the detection precision is improved, deformation and internal flaw detection are carried out in a centralized manner, the operation steps are simplified, and a pretreatment auxiliary assembly can play an auxiliary role in the detection of the deformation detection assembly and before the detection of the flaw detection assembly, so that the detection precision and efficiency are further improved.