The synergistic effects of double doping with a positive mismatch perovskite (Ba2YNbO6) and a negative mismatch perovskite (LaAlO3) on the brittle ceramic YBa2Cu3O7-x (YBCO) superconducting films were investigated. The double-doped sample allows a greater doping amount than any single doping, with significantly smaller nanostrain on the c axis, and shows superior superconducting properties. By analyzing the crystal mismatch and establishing a suitable model of the doping effects, it was found that the double doping with the positive mismatch and the negative mismatch dopant cancels the long-range strain but still generates defects around the interface between the YBCO and the dopants, simultaneously. This result reveals a feasible method for solving the problem of degradation and even cracks in the YBCO film due to the excess doping amount. This approach provides a wider compositional space for the design and fabrication of more ingenious pinning structures in the YBCO film for meeting the criteria of specific applications.