A micro-nano textured graphene-based bionic pH sensor and a preparation method therefor. The micro-nano textured graphene-based bionic pH sensor comprises a substrate (1), a working electrode (4), a reference electrode (5), a copper contact A (6), a copper contact B (7), an inner lead A (8), and an inner lead B (9). A groove A (2) and a groove B (3) are formed in the substrate (1). The working electrode (4) is located in the groove A (2), and the reference electrode (5) is located in the groove B (3). The bottom of the working electrode (4) is connected to the inner lead A (8) by means of the copper contact A (6). The top of the reference electrode (5) is connected to the inner lead B (9) by means of the copper contact B (7). The working electrode (4) comprises a graphene group A (401) and a sensitive electrode material layer (402). The sensitive electrode material layer (402) is located on the upper layer of the graphene group A (401). The reference electrode (5) comprises a graphene group B (501) and a metal material silver layer (502). The metal material silver layer (502) is located on the lower layer of the graphene group B (501). Microgrooves or micro pits are formed in the upper surface of the sensitive electrode material layer (402) and the lower surface of the metal material silver layer (502). The pH sensor can fast adsorb water in soil and a culture medium and then adsorb hydrogen ions, and pH in-situ measurement of the soil, the culture medium and other heterogeneous systems is implemented.