Fractured anticline reservoirs are mostly developed by a line production well located at the top position and a line injecting well located at the bottom position. The production well is often interference with by multiple injecting wells, but there is little related research about multiple injecting well interferences. To solve this problem, an extended bottom-hole pressuredrop (BHPD) response model for production well interfered with by multiple injection wells was presented to capture the injection interference and gravity effect. The proposed model's correctness is validated by the software numerical simulation, and low regimes were identified by the BHPD and its derivative curve. Research results show that: (i) the BHPD derivative curve has a one-half slope line, V-shape, and one slope line in reservoir linear flow regime, inter-porosity flow regime, and interference flow regime, respectively; (ii) the drop rate of pressure increases with the increase of formation transmissibility and storability. The bigger the fracture storability, the more obvious the V-shape feature in the derivative curve of BHPD. As the inter-porosity flow coefficient increases, the V-shape feature emerges later; (iii) the beginning time of the interference flow becomes later when the interference distance increases. When the injection rate trends to the production rate, the BHPD curve shows a slight drop and its derivative curve has an intermittent rupture; (iv) the influence of the gravity effect is not ignored. Due to the gravity effect, the BHPD interfered by constant injection well like the BHPD's behavior interfered by the closed boundary. This work provides technical support for capturing the source and degree of interference from well group in the heterogeneous fractured anticline reservoir.