The present invention provides an auto-developing and regularly-weighted protein molecular weight marker kit, comprising: (a) a plurality of recombinant proteins having formula (I), (B)m-A-(C)n  (I), wherein A is a polypeptide of SEQ ID NO: 1, B and C are independently any mutually identical or different polypeptides with the value of molecular weight being a multiple of 5, and m and n is independently 0 or any integer larger than 0; and (b) one or more solvents for stabilizing the recombinant proteins. The present invention also provides a method for preparing the auto-developing and regularly-weighted protein molecular weight marker kit.