Abstract: We further studied the polytene chromosomes of Anopheles sinensis by improved method of preparation. 527 satisfactory specimens of polytene chromosomcs of the salivary gland were observed and analysed. The short arm of the X chromosomc of XL (Fig. 1-6) was furthcr identified. The frequency and the disposition of the short arm obscrved on preparations were discussed. Statistical analysis shows that the short arm of the X chromosome was present in more than 90 percent of the preparations. The disposition of the short arm on preparations can be divided into following patterns: a. XL linked with XR (Fig. 1); b. XL free; c. XL adhering to other arms of thc autosomal chromosomes (2R, 2L, 3R, 3L Fig. 2-6).