The invention belongs to the field of electric technique, and provides an SC adapter of an improved structure. The SC adapter comprises an outer shell, a plug and a ceramic sleeve, wherein a containing space used for containing the ceramic sleeve is formed in the inner middle position after the plug and the outer shell are assembled, the upper end and the lower end of the plug are respectively provided with a fixing end fastener portion, each fixing end fastener portion is provided with a connector plug, fastener arms will deform and rotate towards the outer side direction when the connector plugs are in interaction with fastener heads, 60-degree inclination is formed between each fastener head and the vertical Y direction, the length of each fastener arm is 5.56cm, and 95-degree inclination is formed between the outer side of each fastener arm and the horizontal X length direction. According to the SC adapter, under the standard precondition that plugging and pulling force is less than 19.6N, pulling-out force is improved to 70N, and good reliability and safety are guaranteed. The whole SC adapter has very few parts and only uses three parts. Due to the design that the plug penetrates upwards from the lower portion of the outer shell and then is fastened through an inclined inverse buckle on the outer shell, the SC adapter has the advantages that few parts are used, production simplicity is achieved, and products are safe and reliable.