The objective of this study was to investigate the pathological characteristics of leukemia patients with secondary myelofibrosis and their relationship with prognosis. The pathological characteristics of 29 leukemia patients with secondary myelofibrosis were observed, the degree of hyperplasia between bone marrow smear and biopsy, as well as the changes of myelofibrosis after treatment were compared, and their relationship with the prognosis was analysed. The results indicated that the myelofibrosis may cause the decrease of pseudoepitheliomatous in bone marrow smear, and the increase of reticulin could be observed except the primary pathological characteristics in the biopsy with Gomori staining ++ - +++, and the secondary myelofibrosis could be alleviated after treatment. The overall prognosis of these patients was poor. It is concluded that the bone marrow biopsy has the important diagnostic value for the leukemia patients with secondary myelofibrosis, and the myelofibrosis can be alleviated after treatment, but the overall prognosis of leukemia patients with secondary myelofibrosis is poor.