要加。the Spring Festival意思是春节。中国传统节日之前要加定冠词the，如the Dragon-Boat Festival 端午、the Mid-autumn Festival中秋节、the Double Seven Festival七夕节。

Spring Festival例句

The Spring Festival is the lunar New Year.

春节即农历新年。

The Spring Festival is only a week away.

离春节只有一周了。

The whole family will get together at Spring Festival.

春节期间全家人都会聚在一起。

Even if you book/ reserve tickets in advance during the Spring Festival, you may still fail to get one.

在春节期间即使提前订票，你也仍可能买不到。

Let's put off our wedding till the Spring Festival.

咱俩的婚事赶年下再办吧。