The present disclosure provided a blood cell analyzer, a control device and a blood analysis method thereof. In the method, a first reagent is mixed with a sample to obtain a first testing sample, and then a second reagent is mixed with the first testing sample for a further reaction to get a second testing sample for basophil classification and/or HGB measurement. A blood sample may be tested in one reaction cell through time-division multiplexing technology to obtain four groups leukocytes classification result and HGB result by single detection channel. Thus, the structure of the analyzer may be greatly simplified on the premise of guaranteeing the performance of the analyzer, the size and cost of the analyzer may reduce and a performance-price ratio of the analyzer may increase.