Pulsed drug delivery (PDD), which can be released at well-defined time points as the therapy needs, can decrease the frequency and avoid taking drug at night, thus improving patient compliance.Here we introduce three kinds of programmed PDD systems independent of external chemical triggering; they are divided according to the triggering mechanisms:degradation-triggered PDD, osmotic pressure-triggered PDD, and both degradationi and osmotic pressure-triggered PDD.This paper reviews preparing technique, release mechanisms and influencing factors of the three PDD systems.The release profiles of pulsatile PDD can be regulated for different therapeutic needs, requiring no external triggers; especially that the PDD system triggered by both degradation and osmotic pressure has a bright future.