Irrational Online Shopping Behavior is defined as "a series of irrational decision-making behavior made by consumers due to the influence of various factors in the virtual web environment". This paper aims to discuss irrational online shopping behavior of an excessive consumption, impulsive consumption and bundled consumption under the influence of mental accounting, and further discusses the internal mechanism of irrational online shopping behavior from the perspective of mental accounting theory: that is, consumers utilize a unique mental account when shopping online and how they mentally code, book, and value this account before, during, and after purchase. Finally this paper seeks to serve as a practical inspiration towards consumers and businesses. 55Open Journal of Social Sciences studies, this paper defines the irrational behavior of online shopping as "in the network environment, a series of irrational decision-making behavior made by consumers under the influence of various factors", and reveals the irrational purchase behavior of over-consumption, impulse spending and bundled consumption in the network environment from the perspective of mental accounting theory. The mechanism of irrational online shopping behavior were discussed: that is, online consumers own an online shopping mental account and how they mentally coding, booking, and valuing this account before, during, and after purchase results in a series of irrational shopping behavior.