Welcome @sunguofeng717, to the community!

I’m afraid I have to tell you that the 1N5711 was discontinued a long time ago. In the datasheet, which is still available online, you can find all the (formerly) guaranteed specifications – though this does not include any information on reverse resistance. The reason applies to all diodes from all manufacturers: a diode is not linear like a normal ohmic resistor, but is non-linear even in the reverse direction, which is why a maximum reverse current is generally guaranteed at a type-specific reverse voltage and a specific temperature (typically 25°C). If you convert this reverse current into a resistance value, it is only accurate at that specific point, i.e. at that test voltage.

The value of max. 0.2μA at 50V stated in the datasheet at the time would therefore correspond to a differential resistance of at least 250MΩ – which, as explained earlier, no longer applies at other reverse voltages.

Does it answer your question?

Regards
/Peter