The invention discloses an auxiliary umbrella installing method and an auxiliary umbrella. The auxiliary umbrella installing method comprises the following steps: step a, the auxiliary umbrella is arranged on umbrella skirts where the auxiliary umbrella needs to be arranged in a sleeved mode; step b, the upper end and lower end, connected with an insulator, of the auxiliary umbrella are blocked, so that a relatively closed space is formed between the auxiliary umbrella and the insulator, and the space is communicated with the outside through vent holes; step c, a glue solution is injected in the space till air in the space is completely discharged from the vent holes, and the space is filled with the glue solution. Beside, the invention further discloses the auxiliary umbrella which is mounted on the insulator, wherein the insulator comprises the multiple umbrella skirts, the auxiliary umbrella comprises fixing parts which cover the upper surfaces of the umbrella skirts, and the fixing parts are connected to the umbrella skirts through binders and provided with the vent holes. According to the auxiliary umbrella installing method and the auxiliary umbrella, the auxiliary umbrella can be firmly fixed to the insulator, so that the service life of the auxiliary umbrella is quite long.