Articular cartilage is mainly composed of cell matrix and water. Proteoglycan gel and type II collagen are the main components of the matrix. According to the biological characteristics of articular cartilage, cartilage tissue engineering scaffolds should have the following characteristics: 1. Positive bio-compatibility, matching with human tissues while meeting the appropriate mechanical strength requirements, not causing damage to patient tissues, and having perfect hydrophilic and degradable properties; 2. Accurately fabricated with an appropriate pore size and the ability to maintain an accurate pore size will allow the fabrication of scaffolds to be suitable. Various scaffolds for tissue engineering applications allow cells to migrate and proliferate in scaffolds, and nutrients to enter scaffolds. Metabolic waste can be discharged from scaffolds through the pores. 3. Highly consistent porous structure, i.e., the pore characteristics, morphology, pore distribution, pore density and connectivity of all three dimensions of scaffolds must be consistent. 4. Stability and mechanical properties to meet the molding requirements. In recent years, many researchers have focused on the development of cartilage scaffold materials and preparation methods to obtain cartilage tissue scaffolds [7; 8; 9; 10]. Hydrogel material has been extensively studied in preclinical and partial clinical studies because it can adjust its mechanical properties to mimic natural tissue. Another main characteristic of hydrogel as a scaffold is that it can maintain the flow state under certain conditions, and crosslink into a solid like shape with certain intensity under certain external stimuli [11; 12; 13]. Sodium alginate is a kind of natural polysaccharide polymer extracted from seaweed, which has high molecular weight, linear shape and high hydration. Therefore, its water-soluble salts have very high viscosity at low concentrations, making it a good thickening and suspending agent. Its molecular chain contains a large number of hydroxyl and carboxyl groups. Under the condition of two valence ions, such as Ca\({}^{2+}\), cross-linked calcium alginate polymers will form, showing that the gel state with high water content is ridiculed [14]. A large number of cell biology experiments show that alginate hydrogel has good compatibility with cells and good mechanical strength; therefore, alginate has often been selected as scaffold material for tissue-engineered bone (cartilage) by many scholars [15; 16]. However, there are many shortcomings in single alginate hydrogel, such as poor biodegradability and relatively few attachment points. After finishing printing, alginate gel is severely contracted and cannot be well molded. Gelatin is a kind of denatured protein, which is hydrolyzed by collagen in the connective tissue or epidermis tissue of animals. The conversion of gelatin between solution and gel is particularly affected by temperature. This characteristic makes it suitable for printing auxiliary materials [4; 17; 18; 19]. In addition, gelatin will not react with calcium chloride, and will produce an intermolecular force to improve the mechanical strength of the material after blending with sodium alginate [20]. In this study, we attempted to combine gelatin and sodium alginate to obtain a composite sodium alginate and gelatin (SA-GEL) hydrogel, then use 3D printing technology to obtain the cartilage scaffolds with good mechanical strength and biocompatibility. In the printing process of fabricating SA-GEL cartilage scaffolds, the printability was determined by many factors, which mainly include two kinds of factors--parameters of the printing material and parameters of the printing setup [21]. Through reasonable material configuration and optimized machine parameter selection, a cartilage scaffold structure that can meet the requirements of mechanical properties and biocompatibility was fabricated. The paper includes the following aspects: 1.