They're more like syllables, not alphabets. There are about 46.
21个声母：b p m f d t n l g k h j q x zh ch sh r z c s 39个韵母 （1）10个单韵母： a、o、e、ê（舌尖前半低，口半开，唇形不圆，如：诶、结业）、i、 u、 ǖ、...
They don't use alphabets like English but they have different words having different meaning.(one word have one meaning)
There is only one alphabet used for English. It is called the Latin alphabet and it has 26 letters.
If you mean by how many letters there are, there are 45 different letters.