Improving the automation level of nuclear power units is the future trend in nuclear power technology development. It not only significantly shortens the time required for various unit operations, bringing considerable economic benefits, but also alleviates the workload of the main control operator, reducing the risk of human error. Currently, the operations involved in unit startup are mostly manually performed, and the main operations from normal cold shutdown to hot shutdown focus on temperature and pressure increase. However, the process of temperature and pressure increase is complex, involving numerous transients and actions, and is subject to limitations such as the P/T diagram and the temperature and pressure increase rates, making it difficult to implement automatic control. This paper, by studying the manual control operations and related control logic of the primary loop temperature and pressure increase process under the NS/SG mode, develops related function designs for automatic temperature and pressure increase, providing reference and guidance for further development of one-button startup designs for nuclear power units.