[Objective] This study aimed to investigate the chemical constituents of walnut leaves. [Methods] The volatile components of walnut leaves were analyzed by head-space solid micro-extraction and coupled with GC-MS. The chemical composition of ethanol extract was identified using ultra-high performance liquid chromatography coupled with quadrupole Orbitrap high resolution mass spectrometry (UPLC-Q-Exactive). [Results] 88 kinds of volatile compounds were identified in walnut leaves, mainly terpenoids, of which sesquiterpenoids account for 78.35%. 30 kinds of active components were identified from ethanol extracts, including twenty kinds of polyphenols (twelve kinds of flavonoids), four kinds of phenylpropanoids, three kinds of pentacyclic triterpenoids, two kinds of essential amino acids and 1 tricarboxylic acid compounds in the ethanol extract in walnut leaves. [Conclusion] The combined use of SPME-GC-MS and UPLC-Q Exactive technology can determine and analyze the chemical composition of walnut leaves systematically, accurately and rapidly.