Plant procedures are instructions to guide operators in monitoring, decision making and controlling for operation of nuclear power plants. While plant procedures historically have been paper-based, the computer based procedures are being developed and applied to overcome the drawbacks of paper-based procedures in many nuclear power plants. Advance Power Reactor 1400 MWe (APR1400) Computerized Procedure System (CPS) has applied at Shin-Kori 3&4 units of Korea since 2012 and recently Shin Kori unit 3 has achieved one cycle trouble free. APR1400 CPS can be classified as type 2 and family 2 based on IEEE standard 1786, IEC standard 62646 respectively. APR1400 CPS has the function to navigate between procedure elements such as procedures, gross steps, steps and instructions and also has many functions mentioned in IEEE standard such as providing process data in the body of procedure steps and process step logic and evaluated data, and access links to soft control and process displays. To maximize the strength of computer-based procedures and to reduce the human errors, procedure based automation is needed. And international standard also states that the next step of computer based procedure is the automation using computer based procedure. Currently APR1400 CPS can support the functions to implement procedure based automation providing the various logic functions such as procedure entry condition monitoring, re-execution condition monitoring for continuous applied step, and automatic evaluation of instructions. To apply procedure based automation, the logic equations are made in the process of procedure writing. This paper introduces the overview of currently APR1400 CPS including the support functions automated and shows the result of partial procedure based automation using Standard Post Trip Actions (SPTA) and Diagnosis Actions (DA) including procedure entry condition monitoring and automatic evaluation of instructions through the Loss Of Coolant Accident (LOCA) scenario. This validation of partial procedure based automation was tested in full scope simulator of APR1400. And this paper also suggests the necessary functions and considerations to implement the procedure based automation.