The invention discloses a preparation method of low-density microfoam temporary plugging agents capable of being charged with nitrogen. A low-cost nitrogen-charging preparation technology is created, and a new way for pump inspection and sand washing operation of a low-pressure high-permeability reservoir is opened up. The preparation method comprises the following steps of weighing 96.5-98 parts of clear water as base fluid by using a measuring cylinder; adding 0.8-1.5 parts of sodium carboxymethyl starch in the base fluid; stirring for 10 minutes at the speed of 3,000r/min; adding 0.4-0.6 part of xanthan gum, 0.15-0.4 part of sodium lauryl sulfate and 0.15-0.4 part of sodium dodecylbenzene sulfonate while stirring at the speed of 3,000r/min; charging nitrogen for 5-10 minutes under the pressure of 0.69MPa; stirring 20 minutes at the speed of 3,000-5,000r/min; and adding 0.4-0.7 part of temporary plugging agents and stirring for 10 minutes.