Large-areasinglecrystallineCuTCNQnanotubearrays(ca.24cm 2 )havebeenfabricatedusinganinsituorganic vapor solid phase reaction by instantaneous heating (TCNQ=7,7,8,8-tetracyanoquinodimethane). The size of CuTCNQ nanotubes can tuned by controlling the reaction temperature. The facile approach provides an important finding for large-area synthesis of vertically aligned array organic nanotubes on conductive substrate, which is crucial to the direct fabricating of electronic and optoelectronic devices for a wide variety of potential applications. The CuTCNQ nanotube arrays exhibited excellent field emission (FE) properties and size-dependent FE properties were observed. The devices based on these highly ordered CuTCNQ nanotube arrays have been demonstrated and have exhibited excellent electrical switching effects. The maximal ON/OFF ratio of CuTCNQ nanotube arrays is about 1100. The morphology-dependent electrical-switching proper- tiesoftheCuTCNQnanotubearrayswereinvestigated.TheseresultssuggestthattheCuTCNQnanotubearraycanbeexpected to find promising applications as field emitters and nanoelectronic devices.