This article describes the support and limitations for vMX as a VNF when installed on a NFX250.  This applies only to NFX250 running nfx-2 software (19.1 and below).

I want to deploy vMX as VNF on NFX250 platform.

Running a vMX as a VNF on NFX250 platform has limited support.  It is only available on 17.4R2 and 18.2R1 through 19.1, and only running nfx-2 software.  The vMX as VNF is not supported on any platforms running nfx-3 software, which includes NFX150, NFX250-NG, and NFX350.  

The vMX as VNF feature runs as a nested VM in lite mode, and has restriction of 1 GB/sec throughput.