Spodoptera frugiperda (SF) is a pest that invaded China since 2019. It mainly eats corn, wheat and other crops, which has caused a great threat to agricultural production and has been highly valued by agricultural department. The study aims at clarifying the population mechanism of SF and its distributions in China. First, a new differential system is developed to simulate the SF evolution process among different age stages and then stability theory is employed to calculate the population reproduction number and analyze the conditions of population extinction and persistent existence. Finally, based on the temperature-based model parameter, the effectiveness of temperature on SF survival is quantified, and the distribution patterns in Chinese provinces are estimated. The results indicate that temperature has a significant effect on the growth and migration of SF, in which SF could not survive when temperature is smaller than 19.6$^{\circ}$C or larger than 35.7$^{\circ}$C. The suitable temperature for SF survival is 24$\sim$28$^{\circ}$C, and when temperature is around 24.3$^{\circ}$C, SF develops fastest. SF is more sensitive to lower or higher temperature. It is further found that the best approach to control SF is reducing spawning rate and accelerating the death rate of adult SF.