The invention discloses a method of processing sour bamboo shoots by combined action of bamboo shoots and mustard. The method comprises the following steps: laying pretreated fresh bamboo shoots and mustard by the way of "one layer of bamboo shoots, two layers of mustard and each layer of salt" to complete laying of raw materials, laying more than three layers of mustard above the top layer afterlaying the top layer of bamboo shoots in a container to completely cover the bamboo shoots, compacting the raw materials with clean weights finally and placing the container with the raw materials atordinary temperature for 10-20 days; when the mustard turns from green to yellow, taking out the bamboo shoots from the container, and storing the original slurry water at the same time; placing the bamboo shoots in the sun for 4-5 days until dried in sunny weather; and then finishing the secondary processing, airing, fumigation and the third airing of the bamboo shoots. According to the present invention, the addition of chemical components is not required in the whole processing process of the sour bamboo shoots, and the prepared sour bamboo shoots are soft and tough, retain the aroma of fresh bamboo shoots, taste sour, crisp and and delicious, and can be eaten directly or fried.