Some advances in organic nonlinear optical (NLO) materials have led to renewed interest in the investigations of this field during past years1-2.A novel organic Second-Order NLO material 4-Ethoxypicoloylhydroxamic Acid (PEHA) has been synthesized.The Kurtz powder measurement shows that PEHAs SHG efficiency is about 2 times as large as that of KDP.X-ray single-crystal structural analyses shows that PEHA belongs to Monoclinic system,space group,Cc,with cell parameters:a =7.4741(16) (A),b =20.535(3) (A),c =6.5000(11) (A),β =117.600(6)°,V=884.1(3) (A)3,Z =4,Dc =1.369 Mg/m3,F(000) =384,μ(Mo Kα) =0.106 mm-1,R =0.0449 for 1955 observed reflections [I > σ (I)],wR =0.0869,GOF =0.997.The one-dimensional structure in PEHA is formed through the intermolecular hydrogen bonds and the hydrogen bond lengths of N(2)-H…O(2a)(a,x,-y+l,z+l/2) and O(2)-H…O(lb)(b,x,-y+l,z+l/2) are 2.807 and 2.595(A),respectively.PEHA exhibits intense fluorescent emission bands at 392 nm (κexc =300 nm) in water solution at room temperature.