In order to explore the effects of different factors on the characteristics of Dendrobium officinale polysaccharide gel， the effects of polysaccharide concentration， gelation temperature， alkali and ion on the characteristics， water retention， acetyl group content of Dendrobium officinale polysaccharide gel were studied. The properties of polysaccharide were characterized by differential scanning calorimetry (DSC)， Fourier infrared spectroscopy (FTIR) and diffractometer (XRD). The results showed that when the mass concentration of polysaccharide increased from 5 mg/mL to 25 mg/mL， its gel strength increased from 70.87 g to 206.39 g， and its water holding capacity increased from 78.52% to 94.25%. When the temperature reached 40 ℃， the maximum strength of gel was 129.29 g， and the corresponding water holding capacity was 90.58%. With the increase of the mass concentration of different alkalis (NaOH， Na2CO3， KOH， K2CO3)， the strength of gel continuously increased at first and then decreased， and the water holding capacity of gel gradually decreased. Under the condition of the same amount of alkali addition， the strength of gel formed was in the order of Na2CO3>K2CO3>NaOH>KOH. In terms of electrolyte， sodium ion could improve the strength and water retention of gel， while urea could significantly reduce the strength and water retention of gel. FTIR spectra showed that the absorption peak intensity of acetyl group group decreased with the increase of Na2CO3 addition. The degree of deacetylation of polysaccharides was related to their alkali content. The XRD results indicated that the diffraction peak intensity was related to the amount of alkali added， and the higher the amount of alkali added， the stronger the diffraction peak. The DSC results indicated that as the amount of alkali increases， the peak temperature of the water absorption peak increases， and the enthalpy value of the peak increases. The mechanism of gel formation may be related to the hydrolysis of acetyl group group promoting the interaction between polysaccharide molecules.