<p>With the rapid development of precision manufacturing technology, the improvement of product appearance design and functional performance has become increasingly important. This study aims to optimize the appearance design of precision manufactured products by combining heat flow simulation with human–machine interaction. The study reviewed the progress of related work and pointed out the shortcomings of traditional design methods in considering thermal characteristics and user interaction. Based on this, a precision manufacturing interactive product rapid design and manufacturing system was constructed, which includes a heat flow simulation model and a management module. Through the verification of simulation results, the system shows superior design accuracy and efficiency compared to traditional methods. In terms of heat flow simulation, we have developed a product manufacturing heat flow simulation model to quantify the impact of thermal characteristics on product design. Introducing the concept of human–computer interaction into the product design module, a new method for rapid product design has been proposed. This method uses an interactive interface to enable designers to quickly adjust the product form and view the potential impact of heat flow on appearance in real time. A series of optimization strategies for the appearance design of mechanical products were ultimately proposed, emphasizing the combination of heat flow management and user experience. The optimization approach focuses on material selection, shape design, and heat dissipation structure, while measures include simulating data-driven decision-making and real-time integration of user feedback. These strategies effectively reduce performance issues caused by thermal effects and provide users with a better product design experience.</p>