As laminar plasma jet has long stable plasma jet, low temperature gradient, negligible noise emission, good processing reproducibility and controllability, it is suitable for industrial applications with high precision requirement. However, the conventional laminar plasma torches are large in size and thus can hardly be applied in processing occasions with space limitation. In this paper, a miniature DC non-transferred arc laminar plasma torch with an external size of about 57 x 56 x 42 mm is proposed to meet the processing requirements in these occasions. It can generate long laminar plasma jet with a maximum jet length of about 300 mm at atmospheric pressure with pure nitrogen. Experimental study on the proposed plasma torch has been carried out to obtain its arc voltage characteristics and the jet length characteristics. It has been founded that the plasma torch with spiral gas flow pattern generally has higher arc voltage and longer jet length than that with axial gas flow pattern. In addition, a special jumping arc voltage characteristic and the variation appearances of the plasma jet were founded, which may be used to design miniature laminar plasma torch with high arc voltage and thus low arc current for the same output power as the conventional ones.