This paper describes a quality-control supply-chain model using the “Internet +” paradigm. The model is based on principal-agent theory, which considers the reputational loss due to inferior products and external responsibility identification. After model analysis and simulation verification, the results show that the optimal quality-control level and market price of agricultural products can be achieved in the agricultural supply chain based on “Internet +” if and only if the information platform’s claim to the agricultural producer is less than the agricultural producer’s claim to the delivery service provider. Also, a rise in consumers’ claims or the agricultural producer’s reputational loss due to inferior products will motivate the quality control of an agricultural procedure. Meanwhile, the market price of agricultural products will also increase with enhanced quality control procedures. The quality-control level of a delivery service provider is inversely proportional to the information platform or its own reputational loss. Thus, the key to promoting quality control along the supply chain is to strengthen the responsibility confirmation of an inferior product between the agricultural producer and the delivery service provider.

With the continuous push for improving packaging efficiency of current packaging practices to prevent losses in a real cold chain, a holistic evaluation method with improved indicators and a conceptual assessment framework to improve packaging efficiency continuously in a fresh vegetable cold chain was proposed. Based on two fresh leafy vegetables with typical packaging practices in a real cold chain in China, the evaluation method was performed and tested from a macro perspective, and then the packaging efficiency constitution with loss prevention perspective was better visualized. The results show that the method can be used for improving the performance of specific packaging efficiency in the fresh vegetable cold chain and improving the suggestions’ sustainability orientation, and systematically summarize their impacts on packaging efficiency; specifically as follows: (1) Since the correlation between the state of fresh vegetables and the environmental stress in the package, the performance of the micro-environment parameters should be given priority for packaging efficiency improvement in loss prevention. (2) Although the use of the packaging materials in current practices was relatively better, it still can improve in food safety and packaging sustainability of the packaging practices through the selection of packaging materials with better sustainability characteristics. (3) Via the visualization of targeted packaging efficiency in cold chain, the fluctuation of loss rates in the cold chain process are well perceived, and there are still room can be performed continuously to realize more efficient packaging for better loss prevention. (4) The method has drawbacks that the optimization of the weights to the given indicators and the indicators based on nutrition and quality of fresh produce was not considered in current research, and it should be strengthened in future research. (5) It is necessary that the perception of differences in targeted packaging efficiency and the consciousness to improve specific packaging efficiency in vegetable cold chain for sustainability.