The invention relates to a soft cut-in method for a non-isolated type photovoltaic grid-connected inverter and an isolated type photovoltaic grid-connected inverter. The method includes the steps of giving a reactive current reference value of a photovoltaic grid-connected inverter according to the magnitude of a power grid voltage and the magnitude of a filtering capacitor, setting an active current reference value as zero, taking the reactive current reference value and the active current reference value as a reference signal of a q-axis current regulator and a reference signal of a d-axis current regulator respectively, taking current signals obtained according to transformation of Park and transformation of Clark as a feedback signal of the q-axis current regulator and the d-axis current regulator respectively, comparing the feed back signals with the reference signals, conducting pre-charge on the filtering capacitor through a current signal which is regulated through a PI regulator and through a reactive current which is output by the photovoltaic grid-connected inverter through control of PWM pulse width modulation, when a voltage output by the photovoltaic grid-connected inverter is consistent with a power grid voltage, an alternating-current contactor is turned off, and soft grid connection is achieved. The soft cut-in method for the non-isolated type photovoltaic grid-connected inverter and the isolated type photovoltaic grid-connected inverter solves the problems that an existing soft cut-in method can only conduct grid connection aiming at the isolated type inverter and has certain limitation, and the grid connection process is complex.