The increasingly complex multi-level functional requirements bring challenges to the design and development of safety-critical airborne software. A formal modeling and analysis method of software requirements with hierarchical semantic characteristics for avionics is proposed. Firstly， a hierarchical formal requirement model is constructed. Hierarchical variable relation model （HVRM） adopts the typical concepts， such as functional module attributes and ports in the engineering domain， to describe the hierarchical feature semantics of system functions， and it also has the formal semantics based on the table form in the original variable relationship model （VRM）， which can represent the semantic information of various types of requirements， including conditional， event-based， and multi-dimensional modes transformation， etc. Especially， consistency and integrity constraints are established based on requirements consistency and integrity demand. Secondly， a processing framework is designed to model engineering itemized requirements into HVRM model， and the processing function and requirement traceability function are implemented and integrated in a hierarchical avionics requirement tools （HART）， which is an airborne software requirement tool platform. Finally， taking an automatic flight control system as a case， the requirements of the flight mode logic function are modeled and analyzed.