In　the　spatial　acoustic　signal　processing,　for　the　issue　of　dimensionality　mismatch　between　2-dimensional　(2D)　sound　field　synthesis　and　practical　sound　source,　and　the　issue　of　near-field　distortion　in　the　near-field　sound　source　synthesis,　this　paper　presents　a　2.5-dimensional　(2.5D)　sound　field　synthesis　method　and　a　modified　Wiener　filter　method　for　near-field　compensation.　The　2.5D　sound　field　synthesis　is　achieved　using　the　spherical　harmonics　expansion　of　higher　order　ambisonics　(HOA).　The　modified　Wiener　filter　is　used　to　compensate　the　near-field　distortion　which　arises　when　HOA　is　utilized　to　reproduce　a　2.5D　near-field　sound　source.　Based　on　the　concept　of　continuous　loudspeaker　array　hypothesis,　a　general　expression　of　the　loudspeaker　driving　signal　is　derived.　The　experiments　show　that　the　proposed　method　reduced　the　relative　error　of　the　synthesized　2.5D　near-field　from　0.23　to　0.031　in　comparison　with　the　cosine　regularization　method.　Meanwhile,　the　proposed　method　provides　a　larger　effective　listening　area　compared　with　the　high-pass　filter　method.　©　2017,　Chinese　Institute　of　Electronics.　All　right　reserved.