<p>Cellulose aerogels have advantages in cost and sustainability. However, it is challenging to alter the single pore size of the majority of cellulose aerogels. The study employed a cost-effective and straightforward ambient pressure drying technique to produce anAl/Si-doped carboxymethyl cellulose composite aerogel characterized by a diverse range of pore sizes. The creation of aerogel pores just encompasses the drying process subsequent to solvent displacement, without any additional leaching procedures being employed. To achieve samples characterized by reduced density and volume shrinkage, the samples with varying substitution degrees of carboxymethyl cellulose and tetraethoxysilane concentrations were prepared. And the study investigated the impact of substitution degrees CMC II, CMC IV, and tetraethoxysilane concentrations on pore size and elucidated the underlying mechanism of microstructure creation. Besides, the result showed that the sample containing the substitution degree CMC II has a greater pore diameter than the sample containing the substitution degree CMC IV. The pore diameters of CMC II and CMC IV samples are at their minimum when the concentration of TEOS is 40%; their respective average pore sizes are 135.26 and 33.37 nm. The research conducted in this work aims to offer valuable insights for the establishment of guidelines pertaining to the control and regulation of pore size in aerogels and to propose a potential method for controlling the distribution of pore sizes, hence enabling the utilization of aerogel in various applications such as sound absorption.</p> Graphical abstract <p></p>