The invention discloses a control optimizing method and device of horizontal well drilling friction and relates to the field of rock-soil or petroleum geology drilling. The control optimizing method of horizontal well drilling friction comprises the following steps that drilling parameters are obtained; according to the drilling parameters of drilling work, a plurality of sets of data samples are obtained through selection; drill column working states corresponding to the data samples are recognized; based on the drilling parameters, the data samples and the drill column working states corresponding to the data samples, the practical friction coefficient of the data samples is obtained; correlation analysis is conducted on the data samples and the practical friction coefficient of the data samples, and parameters, meeting preset requirements, in the drilling parameters are obtained; and the parameters, meeting the preset requirements, in the drilling parameters are adjusted according to preset rules. By the adoption of the control optimizing method and device, the practical friction coefficient can be optimized, and accordingly the real-time drilling efficiency is improved.