Abstract: It is of great practical significance to empirically examine the neighborhood effect in farm households' farmland quality protection behavior and to analyze the moderating role of environmental awareness in farmers' neighborhood effect. This paper aimed to improve farmland protection policies and to guarantee national food security. This paper employed methods that were based on the mechanism analysis. The baseline data from the China Land Economy Survey 2020 conducted in Jiangsu Province were used to empirically test the research hypotheses. The results showed that: (1) There was a significant neighbourhood effect in the farm household's farmland quality protection behaviour. For every 10% increase in the neighbour's per mu fertilizer application, the farm household's per mu fertilizer application would increase by 7.05%, and for every 10% increase in the neighbour's per mu pesticide application cost, the farm household's per mu pesticide application cost would increase by 7.45%. (2) Neighbourhood effects were group heterogeneous in farm households' cropland quality protection behaviours, and neighbourhood effects had a significant positive impact on the cropland quality protection behaviours of low-income and smaller landholding farm households. (3) In the neighbourhood effect of arable land quality protection behaviour, farmers' environmental protection awareness played an important moderating role, and farmers' stronger environmental protection awareness had a significant positive effect on the neighbourhood effect of arable land quality protection behaviour. Based on this, the state should target high-income farmers and large-scale land operators in villages and actively guided them to reduce the application of chemical fertilizers and pesticides. It was also important to lead them through the demonstration of the neighborhood effect, which in turn led to the adoption of arable land quality protection behaviors by other groups of farmers. In addition, the environmental awareness of farmers should also be raised further, which in turn would be helpful in enhancing the neighborhood effect of cropland quality protection.