According to the Gensim Word2Vec, I can use the word2vec model in gensim package to calculate the similarity between 2 words.
e.g.
trained_model.simi
I am using the following method and it works well. You first need to run a POSTagger and then filter your sentence to get rid of the stop words (determinants, conjunctions, ...). I recommend TextBlob APTagger. Then you build a word2vec by taking the mean of each word vector in the sentence. The n_similarity method in Gemsim word2vec does exactly that by allowing to pass two sets of words to compare.