System and method of regenerating diesel particulate filter for mild hybrid electric vehicle

The present invention relates to a soot filter regeneration device and method for a mild hybrid vehicle. According to an embodiment of the present invention, the soot filter regeneration method for a mild hybrid vehicle comprises the following steps of: determining whether a soot filter needs regeneration; regenerating the soot filter if regeneration of the soot filter is necessary; determining whether a coasting condition is satisfied during regeneration of the soot filter; turning off an engine and counting elapsed time from the time when the coasting condition is satisfied if the coasting condition is satisfied; comparing the elapsed time with a set time; and turning on the engine when the elapsed time reaches the set time. The present invention intends to provide a soot filter regeneration device and method for a mild hybrid vehicle, which is capable of effectively regenerating a soot filter by turning on an engine even during coasting when the soot filter needs to be regenerated.