In this paper, we propose open bisimulations for open processes in higher order π-calculus. The equivalence of open bisimulations and other bisimulations for open processes is proved. Furthermore, we present a symbolic operational semantics of higher order open processes, and give some symbolic bisimulations for higher order processes. The relation between symbolic bisimulations and other bisimulations is also studied. At last, we introduce a higher order π-calculuswith sum and conditional operators, then we study open bisimulations and symbolic bisimulations for this calculus.