Power Bi live connection using SSAS service with MySQL DB.

I'm not entirely sure I understand how you are trying to set this up with SSAS. When you say

using SSAS service of power BI

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Are you trying to connect to the internal SSAS instance that Power BI Report Server uses behind the scenes to load pbix files. Or do you have a separate SSAS instance that you've installed.

If you are trying to connect to the internal SSAS instance for Power BI Report Server then you are doing this wrong. You should never attempt to connect to this directly and I'm pretty sure that in most cases it will not work anyway.

If you are just trying to create a model that queries MySQL directly instead of storing the data in import mode then you should be using the MySQL connector, but unfortunately the MySQL does not currently support DirectQuery (see https://docs.microsoft.com/en-us/power-bi/power-bi-data-sources) but there is an open uservoice request for this which you could vote for here https://ideas.powerbi.com/forums/265200-power-bi-ideas/suggestions/19054735-direct-query-with-mysql-databases

So unfortunately your only option if your data is in MySQL is to use an import model (or move your data to another data source, but usually this is not that easy)