Abstract: To study on the germination ability and vigor of the wheat seed at different grain filling stages, some indexes of germination ability of the seeds of different grain filling stage were measured with four wheat genotypes as the experimental material. The results showed that the germination potential and germination rate increased with the progression of grain filling stage. The germination potential and germination rate reached the lowest level in May 8th with mean germination rate of 85%, which was inferior to the other stages’ mean value of more than 93%. These results indicated that the seeds have a strong sprout ability at early grain filling stage. Thousand-grain protein content of four wheat genotypes in six different grain filling stages was also determined. The average thousand-grain protein content was 0.76 g at May 8th and 3.1 g at June 1st. The results clearly showed that thousand-grain protein content differed dramatically between the four genotypes at the six grain filling stages which the former protein content was only 23.5% of the latter. This experimental study demonstrated that when protein content reached about a quarter of the total content of the seed, it have a strong germination ability and vigor.