Abstract: This article attempts to establish a framework of quantitative evaluation method and implement a universal tool (software) for evaluating crop ecological suitability based on the framework. Three improvements were made in quantitative evaluation method: 1) ecological distance calculated with four basic points is used to weigh the fitness of environmental factors, which can represent the thresholds of vital factors and common factors with different basic points; 2) double-threshold-setting method is used in result grading, which can separate the components with obscure ecological meanings from those with obvious ecological meanings; 3) a digital and structured expression of suitability evaluation process is presented. With the improved method, we have developed a universal evaluation tool implementing a quantitative evaluation, which can help agriculture experts without IT engineering knowledge. As an application, we implement a quantitative evaluation of ecological suitability of winter wheat in Beijing area. The experiment shows that the tool can accommodate most kinds of environmental factors as well as evaluation algorithms.