G-DINA model, a generalized model of DINA model, is a compensatory and saturated cognitive diagnostic model. The compensatory characteristic of G-DINA model caters to the multidimensionality of language tests; the saturated characteristic of G-DINA model caters to the abstractness and indivisibility of language skills. Taking the reading test, a typical form of language tests, as the case study, this paper applies G-DINA model to the empirical analysis on the PISA English reading test results of 1029 British subjects. The study verifies two hypotheses: compensatory and saturated cognitive diagnostic models can fit language tests ideally; G-DINA model, a new cognitive diagnostic model, can be applied to diagnose complicated and abstract language tests and the results of analysis can be interpreted both statistically and linguistically.