This paper presents a novel adaptive terminal sliding mode guidance law tailored for strapdown-guided missiles, designed to achieve precision strike requirements in modern warfare. The proposed guidance algorithm accounts for two critical constraints: terminal impact angle and seeker’s field-of-view (FOV). Based on sliding mode control theory, the proposed method develops a rapidly converging guidance law that effectively reduces miss distance while consistently satisfying the desired impact angle constraint. A dynamic model describing the relative motion of missile-target is formulated, and a dynamically adjustable sliding surface is designed to enhance the guidance adaptability and accuracy against highly maneuverable targets. The approach ensures that the target remains within the seeker’s FOV constraints throughout the engagement process. Simulation experiments validate the performance of the proposed guidance strategy, demonstrating its effectiveness in meeting terminal constraints and achieving accurate interception. Compared to Proportional Navigation Guidance (PNG), this method possesses superior robustness and adaptability, making it extensively applicable for complex, maneuverable target scenarios.