With the Attraction Market Share Theory as the foundation and the Multiplicative Competitive Interaction （MCI） Model as the method, this article studies the effects of brand, price and sales promotions on market share of women＇s sanitary towel, and calculates the brand value, price elasticity and promotion elasticity as well. The study results show that brand has the strongest effect, followed by promotion, and the effect of price is relatively small. Although promotion has been carried out frequently, none of the promotion plans for any of the brands is optimal; the low-effect promotions have been used more broadly and frequently, but high-effect promotions have been used less frequently, ff the firm could optimize the allocation of promotion resources, the return on promotion would be increased to certain extent, even though there would be no increase of investments on promotion