This Study will introduce the concept of A TP(A vailable To Promise) and CTP(Capable to Promise) through the existing study, the process analysis of CTP, the modeling of algorithm and the embodiment of system. This research considers the environment of using Job-Shop method. The CTP algorithm models using LPST(Latest Possible Start Time) and EPST(Earliest Possible Start Time) method especially. It is important part of executing CTP systems. The CTP modeling and implementing develops to system which is capable to implement in the various business environment through additional and continuous research.