The invention discloses a method, a device and a terminal device for reselecting and measuring a cell. The method comprises the following steps: firstly, confirming an effective measuring parameter for reselecting and measuring the cell, wherein the effective measuring parameter is used for indicating the information of time period required for the condition that the result of the next reselecting and measuring of the cell meets a switching or reselecting condition; confirming the information of triggering time of the next reselecting and measuring of the cell according to the corresponding effective measuring parameter; and triggering an operation of reselecting and measuring the cell on the basis of the information of triggering time. According to the embodiment of the invention, by monitoring the effective measuring parameter for reselecting and measuring the cell, the triggering time for reselecting and measuring the cell is adjusted, so that the possibility of performing an invalid operation for reselecting and measuring the cell by a terminal is reduced to a certain extent, the consumption of invalid electric energy of the terminal is effectively reduced, the electric energy of the terminal is saved and the stand-by time of the terminal is prolonged.