Sodium carboxymethyl cellulose (CMC) has received a tremendous amount of attention because of its outstanding solubility in water. In this study, the deconstruction behavior of a fibrous CMC network in water was expressed with kinetic models. The experimental results suggested that the water adsorption process was the key factor in the deconstruction of a fibrous CMC network, and it was controlled by the physical adsorption, which was confirmed by the high correlation coefficient (R2 > 0.95) of the pseudo-first-order kinetic model. The dissolving behavior of a fibrous CMC network in water was monitored with the focused beam reflectance measurement technique, which showed that the whole process included the network deconstruction and dissolution of the fibrous CMC itself. The CMC network dissolving process consisted of three periods: a deconstruction period (t0 to t1), deconstruction and partial dissolution period (t1 to t2), and partial dissolution period (after t2). The first deconstruction period (t0 to t1) was the key period that controlled the dissolving efficiency of the water-soluble handsheets. The deconstruction period was 17 s for the CMC with a degree of substitution (DS) of 0.80, while it was 34 s for the CMC with a DS of 0.50.