Traditional agricultural chassis have poor mobility and adaptability to hilly orchard terrain. To address this, a tracked bilateral coordinated swing-arm power chassis was developed, enabling adaptive track lifting and swinging via a spatial linkage mechanism, with hydraulic power supplied to front-mounted implements. Based on the operational characteristics of hilly orchards, such as dispersed plots and narrow inter-row passages, the overall configuration and dimensions were systematically designed. A bilateral coordinated swing-arm mechanism was proposed to enhance adaptability and driving stability on uneven terrain, and key components were optimized and matched to ensure coordinated operation. The chassis performance was evaluated through multi-body dynamic simulations and field experiments under typical hilly orchard conditions. Simulation results verified the strong adaptability of the proposed mechanism to terrain undulations, while experiments demonstrated that the driving stability on rough terrain was improved by 61.29% compared with that of a conventional crawler chassis. The developed chassis achieved a straight-line deviation rate of 4.03% and a minimum turning radius of 725.8 mm. It was capable of stable uphill, downhill, and lateral movement on slopes up to 16° without overturning or slipping and exhibited smooth obstacle-crossing performance. The implement mounting system provided a lifting range of -5°~32° and a lateral adjustment of 100 mm. During continuous weeding operations, sufficient power output and a low hydraulic oil temperature rise indicated reliable thermal behavior and suitability for long-term orchard applications.