Sidetracking of old wells is one of the important means to increase efficiency in old oil fields, which can utilize remaining oil. At present, the traditional well selection method is for oilfield engineers to select wells based on experience and relevant dynamic and static data. Its main disadvantages are large workload and strong subjectivity, which are not conducive to promotion and use. In response to this issue, this article applies the grey correlation method to determine weights and establishes a lateral drilling well location optimization method that includes four aspects: optimizing evaluation parameters, determining the weights of parameters, calculating decision coefficients, and grading decision coefficients. This method can provide standardized and quantitative selection criteria for lateral drilling, optimize the selection of lateral drilling, have strong operability, and the calculation results can meet the on-site compliance rate of up to 95%.