The embodiment of the present invention provides a data voltage adjusting method of a liquid crystal display panel, comprising: obtaining a total variation amount of data voltages on all data lines in the liquid crystal display panel; calculating a maximum variation amount of the data voltages corresponding to a horizontal crosstalk index according to the horizontal crosstalk index of the liquid crystal display panel; determining whether an absolute value of the total variation amount of the data voltages is larger than an absolute value of the maximum variation amount of the data voltages corresponding to the horizontal crosstalk index; if yes, implementing a data voltage adjustment to data lines, in which with data voltages having variations in the liquid crystal display panel according to the total variation amount of the data voltages. The embodiment of the present invention further provides a data voltage adjusting device of a liquid crystal display panel.