>>1976032both Buddhism and Socialism are systems are ultimately concerned with liberating people from suffering, by means of analysing conditions and then removing the causes of suffering via praxis.
i am assuming you already know about Socialism since you're posting here, and how it aims to minimise suffering by eliminating the exploitative system of capitalism, imperialism, discrimination, private ownership, accumulation of wealth and power by elites, which leads to the conditions the proletariate finds itself in.
Buddhism is also focused on liberating oneself from suffering, and following the path to doing so, which means following the path of the Buddha, which is the middle-way of avoiding extremes of indulgence or self-induced austerity, avoiding violence, non-attatchement to negative to temporary things, living in a way that doesn't harm yourself or others, practicing mindfullness and meditation.
And such many people see the two as fitting together very well. Both seek to elimanate suffering, Socialism by eliminating the external forces that cause it on an international socio-economic scale, Buddhism on a personal scale by examining the means of how we live, our awareness, our insight, by understanding our minds.