A method of using microporous filter membrane (nuclepore membrane) to filtrate a dilute solution under low pressure is established to study the size and conformation of linked polymer coils (LPC) in solution made up of the low concentration partially hydrolyzed polyacrylamide (HPAM) and aluminum citrate (AlCit,crooslinker)．The results show that the LPC is spherical．Because of the crosslinking the metamorphism of the LPc under shear is limited．Integrating the method of filtration with dynamic light scattering (DLS) and scanning electron microscope (SEM) could reveal the size distribution of the LPC．The results show that the diameter of the LPC in solution (the relative molecular weight of HPAM is 1.1×107～1.4×107,the concentration of HPAM is 0.02％,the concentration of NaCl is 0.2％,the mass ratio of HPAM to Al is 20:1) is less than 1.38 μm,the diameter of a few LPC is more than 450 nm,and the mean hydrodynamic diameter of the LPC is 492 nm．In this range of concentration of HPAM and with the same experimental condition,the higher the relative molecular weight of HPAM,the larger the size of the LPC．Since the shrinkage of the LPC on glass sheets after drying spontaneously is limited the photographs of SEM of the LPC could describe the real size distribution of the LPC．