Aiming at the problem of declining packet delivery rate (PDR) and sharp increase in energy consumption of large-scale LoRa networks, a LoRa spreading factor (SF) and coding rate (CR) allocation method based on weighted utility function is proposed. Firstly, the coupling influence relationship between SF and CR on PDR and energy consumption is established. Then, the utility functions of PDR and energy consumption are established based on the reward and punishment mechanism, and their weighted values are taken as the objective function, and the greedy algorithm is used to jointly allocate the SF and CR. Finally, the optimal weight coefficient is determined by traversing the search. The simulation results show that compared with the latest CA-ADR algorithm, the proposed algorithm obtains a 21.2% increasment in terms of the average PDR, and a 165% increasement of the average energy efficiency. The algorithm in this paper effectively improves the communication reliability and life cycle of terminal devices in LoRa networks, and has high application value in many scenarios such as smart cities and smart agriculture.