The invention discloses a novel process for producing high-purity lithium hydroxide by salt lake brine. The process comprises the following steps that A, and the process comprises the following operation mode that the process adopts continuous operation, wherein the scale of each device is optimized through the data calculated by the process, the operation mode is optimized, so that continuous operation is achieved; and B, the salt lake brine is subjected to lithium extraction (by an adsorption method or an electrodialysis method), lithium-magnesium separation, purification and reverse osmosispre-concentration to obtain a lithium chloride qualified solution, and the reverse osmosis pre-concentration qualified solution comprise the following raw materials of, 35-50 g/L of lithium chloride,lower than 10 mg/L of calcium-magnesium ions, and lower than 200 mg/L of boron ions. According to the method, (an adsorption method or a membrane method) ), the magnesium chloride solution subjectedto lithium extracting by brine, magnesium removal and reverse osmosis pre-concentration is taken as the raw material, the electrodialysis technology, a reverse osmosis technology, a resin adsorption technology, an ion membrane electrolysis technology, an evaporative crystallization technology and the like are adopted, so that the high-purity lithium hydroxide product is produced, and therefore cyclic utilization of salt lake lithium resources is guaranteed.