The present invention provides a fertilizer composition for improving fruit quality and fruit thinning, a fruit thinning method, and a preparing method. The fertilizer composition is characterized by including: i) a fermented product of a medical herb mixture including Houttuynia cordata Thunbandlower grade ginseng； ii) seaweed extract； andiii) amino acids, causing unnecessary flowers to drop, having no harmful effect on bees and flower-visiting insects； not inhibiting the fertilization of flowers, causing no damage to plants, having no flower bud pinching, flower thinning and fruit thinning effects except for the right time for treatment, thereby making it possible to reduce labor costs, lead to an increase in production of large high-quality fruits having high fruit sugar content, and contribute to an increase in fruit farmhouse income through the maximum flower bud pinching, flower thinning and fruit thinning rates of about 90%.
