In this presentation, we investigate the attosecond transient absorption spectroscopy of both singly and doubly excited states in helium atoms subjected to an extreme ultraviolet (XUV) attosecond pulse and a time-delayed infrared (IR) few-cycle laser.Model calculations by numerically solving the time-dependent Schrodinger equation based on a one-dimentional (1D) 2e model agree qualitatively with the recent experimental observations,which indicate that the simple model is an effective scheme to describe some of the essential physical mechanisms at work.Three-level models are used to identify the underlying physical mechanisms.We further compare the transient photoabsorption spectrum calculated with le (single-active-electron approximation) and 2e systems for singly excited states and find a ~l00as discrepancy for the two sets of calculations, which is related to the relaxation time from He to the ground state of He+ after one electron being striped off.