Deep penetrating hydraulic fracturing with chemical treatment is the main technology to remove deep plugging in unconsolidated sandstone reservoirs. Fracability of unconsolidated sandstone and influencing factors of fracture propagation are key points to this technology. In this paper, hydraulic fracturing tests with different viscosities and various injection rates are carried out to analyze their effects on fracture initiation and propagation. The results show that: 1) With low injection rate and viscosity, pore channel expansion and permeability enhancement occur in the interior of unconsolidated sandstones, though there are no obvious fractures. 2) Hydraulic fracturing can be achieved in high-permeability unconsolidated sandstone using high viscosity fracturing fluid under high injection rate. The threshold value of injection rate and viscosity of fracturing fluid increase with the increase of rock permeability. 3) There are three types of fractures: tensile fracture, shear fracture and mixed fracture, and with the increase of the viscosity and injection rate of fracturing fluid, the morphology of hydraulic fractures evolves in the trend of ‘tensile failure-mixed failure-shear failure’. 4) Adjusting the viscosity and injection rate value slightly higher than the threshold value can realize the generation of deep penetrating fractures in unconsolidated sandstones. Results in this paper can provide relevant theoretical support for field hydraulic fracturing design of unconsolidated sandstone reservoirs.