In order to explore the relationship between drug grafting ratio of polymeric prodrug and its drug loading efficiency, molecular dynamics simulation is utilized to calculate the compatibility of polymeric prodrug with 5‐aminolevulinic acid methyl ester (m‐ALA) and H2O first. Then, dissipative particle dynamics simulation is used to observe the morphologies of drug‐loaded micelles. Then, designed polymeric prodrugs are synthesized, drug‐loaded micelles and blank micelles are prepared by dialysis method, and the drug loading content (DLC) and encapsulation efficiency are measured. The computer simulation shows that polymer–drug compatibility gets better as the m‐ALA grafting ratio increases from 0% to 100%. Experimental results show that the DLC of micelle changes from 4.05% (0% grafting ratio) to 8.99% (100% grafting ratio). Through comparison, the experimental results are proven to be consistent with the computer simulation results, revealing that the drug loading efficiency of polymer micelles could be improved by grafting drugs.