The present application provides a negative electrode active material, a secondary battery comprising the same and an electrical device, wherein the negative electrode active material comprises a matrix material and a silicon-based material, the matrix material comprises a plurality of pore structures, at least a part of the silicon-based material is located in pore structures of the matrix material, at least a part of the silicon-based material has a crystalline structure, the silicon-based material comprises a first silicon-based material and a second silicon-based material with different grain sizes, and a ratio of grain size of the first silicon-based material to grain size of the second silicon-based material is greater than or equal to 1.6. The negative electrode active material can result in a secondary battery having high energy density, high First Coulombic Efficiency, long cycle life and long storage life at the same time.