After carefully reading the mlt parameters here https://wiki.apache.org/solr/MoreLikeThis
I found that I can specify the following parameters to return "bbb" when search for similar documents of "aaa": mlt.mintf=1 mlt.mindf=2 Details: mlt.mintf: Minimum Term Frequency - the frequency below which terms will be ignored in the source doc. DEFAULT_MIN_TERM_FREQ = 2 mlt.mindf: Minimum Document Frequency - the frequency at which words will be ignored which do not occur in at least this many docs. DEFAULT_MIN_DOC_FREQ = 5 Hope this is helpful to those who are confused about the mlt returns. -- View this message in context: http://lucene.472066.n3.nabble.com/Solr-mlt-doesn-t-return-documents-with-exactly-the-same-contents-tp4171284p4171399.html Sent from the Solr - User mailing list archive at Nabble.com.