The invention relates to a high-flow and low-lift water pump used in medium-and large-scale water conservancy projects, and discloses a pull-rod modularized guide vane type diagonal flow pump. The diagonal flow pump comprises parts of square outer barrel and inlet pipe connecting sections, square outer barrels, pull rods, impeller blades, blade hubs, guide vane hubs, guide vane blades, streamlined ribbed plates, a pump shaft, guide vane body flanges, hydrocones, screws, press plates, oil seals, bend pipe sections, rolling bearings, mechanical seals, couplers and the likeother parts. The diagonal flow pump is characterized in that impeller casings and guide vane body outer walls are integrated to form the outer barrels, a cross section of each outer barrel adopts an square outside and round inside shape, the left sides of the outer barrels can be directly clamped in the connecting sections for positioning, so that fast butt joint is achieved, and the left sides require no fastening part; and moreover, the right sides of the outer barrels are connected and fixed with the guide vane body flanges and flanges on the left sides of the bend pipe sections through the pull rods and the nuts. Pull-rod connection is adopted, the guide vane bodies are connected with the outer barrels and the bend pipe sections, therefore, compared with a traditional diagonal flow pump, the pull-rod modularized guide vane type diagonal flow pump is more convenient to dismount and mount, facilitates maintenance and detection, and can be used for observing cavitation bubbles produced due to internal cavitation of the diagonal flow pump.