A whole blood measurement method associated to hematocrit (HCT) and a whole blood measurement circuit thereof is applied in the detection of HCT of a whole blood sample to be tested. Herein, a time to digital converting circuit (TDC) is used for counting charging time or discharging time of a fixed capacitor and a to-be-tested sample, and a capacitance difference that is related to HCT is generated according to the charging time or the discharging time, so as to provide a reference for a whole blood feature test.