A toner reproduction curve (TRC) control method is provided. The TRC method for controlling a printer including a color toner density (CTD) sensor includes the steps of (a) measuring a development potential VB, a charging potential VO, an exposure potential VR, and a development current Id and evaluating a development vector VD, which is the difference between the development potential VB and the exposure potential VR, and a backplating vector VBP, which is the difference between the charging potential VO and the exposure potential VR; (b) forming a TRC space using TRC data detected from the CTD sensor; (c) obtaining a TRC characteristic function from the TRC data, the development vector VDnullx, the backplating vector VBPnully, and the development current Idnullz; (d) forming an RTRC by setting TRC data, whose covariance is smaller than a threshold value among the detected TRC data, as RTRC data; and (e) measuring TRC data, comparing the measured TRC data with the RTRC data to calculate control parameter values, and controlling the printer using the control parameter values. The TRC method does not require other sensors but the CTD sensor. By using internal parameters covering environmental changes, the charging potential of a photosensitive body, a state of a developer, and the efficiency of a charger can be estimated, thereby realizing efficient TRC control.