With the increasingly widespread application of airborne software in civil aircraft and the continuous growth of its functional complexity, the frequency of software modifications has risen significantly. The traditional factory-return loading mode leads to high operating costs and long maintenance cycles. Focusing on the design of field-loadable software for civil aircraft, this paper proposes a decision-making strategy for determining whether airborne software should be designed as field-loadable software. This strategy classifies airborne software into three categories, platform basic software, functional software, and database software. It puts forward the design principle that field-loadable design is mandatory for database software, preferred for functional software, and not mandatory for platform basic software. In addition, a multi-dimensional design deviation assessment model is constructed for software that cannot meet the above requirements. Functional software that is not designed as field-loadable and has not yet been installed on aircraft shall be evaluated from five dimensions: interconnection complexity, software characteristics, airline operation, commercial off-the-shelf (COTS) attributes, and competitor aircraft models. For functional software that is not designed as field-loadable but has already been installed on aircraft, three additional evaluation dimensions shall be included: the possibility of software modification, difficulty of optimization, and cost of optimization. Meanwhile, this paper analyses the airworthiness requirements to be considered in the design of field-loadable software, as well as the design considerations required to address problems arising in the delivery process, such as configuration identification Issue, granularity issue of field-loadable software packages and format issue of field-loadable software packages. The research provides a systematic reference for the design decision-making, airworthiness compliance and efficient delivery of civil aircraft field-loadable software, helping to shorten aircraft downtime and reduce airline operation costs.