The invention discloses a shaft type part length measuring device. The shaft type part length measuring device comprises a work station and measuring parts mounted on the work station, wherein the measuring parts comprise a material holding assembly, a top pin assembly, a grating measuring assembly and a shaft type part length measuring device, the measuring parts comprise a material holding assembly, a top pin assembly, a grating measuring assembly, a positioning pin, a positioning pin support, a guide bar and a leaning plate, the material holding assembly comprises a rotating disc and a clamping sleeve, the top pin assembly comprises a top pin shaft, a top pin shaft support, a length measuring cylinder and a pad, and the grating measuring assembly comprises a scale grating, a grating reading head and a reading head support. The measuring device is advantaged in that the grating measuring method is employed, automatic, rapid and high-precision measurement of the length of the shaft type part can be carried out, disadvantages of manual measurement of a vernier caliper are solved, part measurement efficiency is effectively improved, and labor intensity of operators is reduced.