Hilly and mountainous regions constitute a vital part of China’s agricultural production landscape. However, their complex natural environments pose unique challenges for the deployment of agricultural machinery. Existing machinery often suffers from poor mobility, low operational efficiency, and inadequate adaptability in these areas, thereby hindering agricultural modernization. This paper addresses the specific characteristics of agricultural production environments in hilly and mountainous regions, thoroughly analyzing how factors such as terrain, soil conditions, and crop types influence machinery design. It explores the theoretical foundations and a collaborative framework integrating adaptive design with lightweighting strategies. By focusing on adaptive design of the working system, running gear, and control system—and combining this with material selection for lightweighting, structural optimization, and integrated design approaches—the study establishes a co-optimization model that jointly considers adaptability and lightweighting. The coupling relationship between these two objectives is analyzed, and appropriate algorithms are selected to achieve optimal solutions. The findings provide theoretical support and practical guidance for the development of specialized agricultural machinery tailored to hilly and mountainous regions, offering significant implications for enhancing agricultural productivity and promoting sustainable agricultural development in these areas.