The colorimeter was used to measure the values of L^* （brightness），a^* （redness-greenness） and b^* （yellowness-blueness） in petals of marigold （Tagetes erecta） to establish a rapid method for determining the lutein content in petals of marigold.The color coefficients including a^*/b^*，（a^*/b^*）²，chroma value，hue value and shade value were calculated.UV-spectrophotometry combined with HPLC method was used to determine the lutein content in petals.The correlation between the lutein content and the color coefficients was analyzed.The regression equation was established and confirmed.The results showed that the lutein content in petals of marigold was significantly correlated with a^*、a^*/b^*、（a^*/b^*）²，hue value and shade value.The regression equation between the lutein content and a^* value constructed by cubic function model had the highest degree of fitness，and there was no significant difference between the predicted value and the measured value of the lutein content.It is indicated that the cubic function model based on a^* value can quickly and non-destructively predict the content of lutein petals of marigold.