The invention relates to a pyrazolo[3,4-c]pyridine derivative. The invention relates to a compound represented by a formula (I), a tautomer thereof, an optical isomer thereof or a pharmaceutically acceptable salt thereof, wherein the formula (I) is shown in the description, and Z, X, RNc, RNd, RNe and RNf are defined according to the claim 1. The invention further relates to the pharmaceutical composition contain the compound. The invention further relates to use of the compound or the pharmaceutical composition in preparing a drug for preventing and/or treating a disease which inhibits positive influence of an Xa factor, particularly use in preparing the drug for preventing and/or treating the disease which inhibits positive influence of the Xa factor under the condition of low hemorrhage risk.