Temperature is one of most important climatic factors in the plant flowering time. Using phenology observed data of rape petal in Gaochun from 1986 to 2016, this paper analyzes the characteristics of fullbloom stage and temperature factors in different years. Path analysis method is used to analyze the effect of three temperature factors on fullbloom stage of rape petal. The three factors are days of mean air temperature lower than 5℃, accumulated temperature of mean air temperature lower than 5℃, and days with strong cold air. The results could provide theoretical foundation for the predicting of optimum viewing period and tourism meteorological services of rape petal in Gaochun. Finally, the results show that there is no fluctuation of fullbloom stage before 2001. However, along with the decadal variation, it shows an early trend obriously. The type of fullbloom stage changes with the average temperature stabilized at 5°C. Specifically, the early years of fullbloom stage are less than normal early years and normallate years, less than normal years, and less than later years. There is a significant correlation between fullbloom stage in late years and days of mean air temperature lower than 5℃ (Ta<5℃). Beginning from the winter solstice, the fullbloom stage of rape petal next year would be later than April 4 if the Ta<5℃ days are more than 53 d, or accumulated temperature of mean air temperature lower than 5℃ (Ta<5℃) is more than 137℃?d. Then, rape fullbloom stage next year would be pushed back with the more days reaching level of strong cold air. With three indice of low temperature, the largest factor impact on rape petal fullbloom stage is the accumulated temperature of mean air temperature lower than 5℃ (Ta<5℃).