I want to split some curves at particular length using node split curve at parameter at 1000 mm but result first curve with total length and second with 0 length .

parameter should be between 0 to 1

You are using SplitByParameter. If you want a better look at what it does, follow the link to the Dynamo dictionary. To paraphrase, when using any parameter on a curve, it is a value of 0 to 1, where 0 is the start and 1 is the end. For example, a parameter of 0.5 would be the halfway point on a curve.

In your graph, you are giving it a parameter of 1000, which caps at 1, so you get the entire line. Instead, you want to find what parameter would be at a length of 1000 on each curve.

Try using ParameterAtSegmentLength first to get the parameters that you can then feed into SplitByParameter.

Everything said before is correct. If you want to split the curve every X distance, you need to create a sequence of number.

If you need the points on curve, because you want to place a family at a fixed distance, you can use Curve.PointsAtSegmentLenght

All posts are very help full.

Thanks all for reply.