Biopolymers combined with 3D printing technology for tissue engineering have been extensively used in many biomedical applications such as organ and tissue regeneration. The 3D printing technology generally relies on a continuous dispensing process, which is usually known as complicated dynamic processes. This is primarily caused by the rheological properties of materials. In addition, the primary concern for biopolymer printing is the time-dependent variation of material properties such as viscosity during the printing process. The variation of rheological properties significantly affects the printing process especially the volume flow rate control. In general, the measurement of rheological properties is carried out before the dispensing process. The setting up of fluid flow control is usually performed according to parameters derived from the premeasured rheological values. However, such a method may not provide optimized parameters for printing control with some biopolymers. An innovative method of measuring rheological properties is proposed in this paper. An image processing procedure is employed to determine the fluid flow at a certain time in the fluid dispensing process. Experiments were carried out in which the rheological properties of poly-(vinyl alcohol) (PVA) and poly-(vinyl alcohol)/chitosan (PVA/CS) aqueous solutions used for dispensing the polymers were evaluated at different time stamps and applied pressures. The measured flow rates were used to construct a pressure-dependent fluid flow rate curve as a function of time to identify the rheological properties of fluid materials under specific times and conditions.