The invention discloses a laser-desorption ion source laser path which comprises a laser fiber head regulator obliquely arranged above the left of an ion source cavity, wherein a lens group bracket is arranged below the laser fiber head regulator; a plano-convex lens for collimation, a biconvex lens for focusing, a negative meniscus lens for focusing and a positive meniscus lens for focusing, which are coaxial with the primary optical axis of the laser fiber head regulator, are sequentially arranged on the lens group bracket; when the incidence fiber diameter is 0.2mm and the incidence divergence angle is 24.5 degrees, the focus diameter reaches 50-120mu m; and when the power of incident light is 1W, the average power density at the focus can reach 160-252W/mm<2>. In the invention, the structure is simple, the production cost is low, the parameters, such as a focus area and focus energy density of the laser path, are optimized, the situations, such as excitation misoperation caused by an oversized laser path focus and an unsatisfactory waveform obtained after excitation are avoided, and the service life of a laser transmitter is prolonged.